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SYSTEMD.NETWORK(5) systemd.network SYSTEMD.NETWORK(5)
systemd.network - Network configuration
network.network
A plain ini-style text file that encodes network configuration for
matching network interfaces, used by systemd-networkd(8). See
systemd.syntax(7) for a general description of the syntax.
The main network file must have the extension .network; other
extensions are ignored. Networks are applied to links whenever the
links appear.
The .network files are read from the files located in the system
network directories /usr/lib/systemd/network and
/usr/local/lib/systemd/network [1], the volatile runtime network
directory /run/systemd/network and the local administration
network directory /etc/systemd/network. All configuration files
are collectively sorted and processed in alphanumeric order,
regardless of the directories in which they live. However, files
with identical filenames replace each other. It is recommended
that each filename is prefixed with a number smaller than "70"
(e.g. 10-eth0.network). Otherwise, the default .network files or
those generated by systemd-network-generator.service(8) may take
precedence over user configured files. Files in /etc/ have the
highest priority, files in /run/ take precedence over files with
the same name under /usr/. This can be used to override a
system-supplied configuration file with a local file if needed. As
a special case, an empty file (file size 0) or symlink with the
same name pointing to /dev/null disables the configuration file
entirely (it is "masked").
Along with the network file foo.network, a "drop-in" directory
foo.network.d/ may exist. All files with the suffix ".conf" from
this directory will be merged in the alphanumeric order and parsed
after the main file itself has been parsed. This is useful to
alter or add configuration settings, without having to modify the
main configuration file. Each drop-in file must have appropriate
section headers.
In addition to /etc/systemd/network, drop-in ".d" directories can
be placed in /usr/lib/systemd/network or /run/systemd/network
directories. Drop-in files in /etc/ take precedence over those in
/run/ which in turn take precedence over those in /usr/lib/.
Drop-in files under any of these directories take precedence over
the main network file wherever located.
The network file contains a [Match] section, which determines if a
given network file may be applied to a given interface; and a
[Network] section specifying how the interface should be
configured. The first (in alphanumeric order) of the network files
that matches a given interface is applied, all later files are
ignored, even if they match as well.
Note that any network interfaces that have the ID_NET_MANAGED_BY=
udev property set will never be matched by any .network files –
unless the property's value is the string "io.systemd.Network" –
even if the [Match] section would otherwise match. This may be
used to exclude specific network interfaces from
systemd-networkd's management, while keeping the [Match] section
generic. The ID_NET_MANAGED_BY= property thus declares intended
ownership of the device, and permits ensuring that concurrent
network management implementations do not compete for management
of specific devices.
A network file is said to match a network interface if all matches
specified by the [Match] section are satisfied. When a network
file does not contain valid settings in [Match] section, then the
file will match all interfaces and systemd-networkd warns about
that. Hint: to avoid the warning and to make it clear that all
interfaces shall be matched, add the following:
Name=*
The following keys are accepted:
MACAddress=
A whitespace-separated list of hardware addresses. The
acceptable formats are:
colon-delimited hexadecimal
Each field must be one byte. E.g. "12:34:56:78:90:ab" or
"AA:BB:CC:DD:EE:FF".
Added in version 250.
hyphen-delimited hexadecimal
Each field must be one byte. E.g. "12-34-56-78-90-ab" or
"AA-BB-CC-DD-EE-FF".
Added in version 250.
dot-delimited hexadecimal
Each field must be two bytes. E.g. "1234.5678.90ab" or
"AABB.CCDD.EEFF".
Added in version 250.
IPv4 address format
E.g. "127.0.0.1" or "192.168.0.1".
Added in version 250.
IPv6 address format
E.g. "2001:0db8:85a3::8a2e:0370:7334" or "::1".
Added in version 250.
The total length of each MAC address must be 4 (for IPv4
tunnel), 6 (for Ethernet), 16 (for IPv6 tunnel), or 20 (for
InfiniBand). This option may appear more than once, in which
case the lists are merged. If the empty string is assigned to
this option, the list of hardware addresses defined prior to
this is reset. Defaults to unset.
Added in version 211.
PermanentMACAddress=
A whitespace-separated list of hardware's permanent addresses.
While MACAddress= matches the device's current MAC address,
this matches the device's permanent MAC address, which may be
different from the current one. Use full colon-, hyphen- or
dot-delimited hexadecimal, or IPv4 or IPv6 address format.
This option may appear more than once, in which case the lists
are merged. If the empty string is assigned to this option,
the list of hardware addresses defined prior to this is reset.
Defaults to unset.
Added in version 245.
Path=
A whitespace-separated list of shell-style globs matching the
persistent path, as exposed by the udev property ID_PATH.
Added in version 211.
Driver=
A whitespace-separated list of shell-style globs matching the
driver currently bound to the device, as exposed by the udev
property ID_NET_DRIVER of its parent device, or if that is not
set, the driver as exposed by ethtool -i of the device itself.
If the list is prefixed with a "!", the test is inverted.
Added in version 211.
Type=
A whitespace-separated list of shell-style globs matching the
device type, as exposed by networkctl list. If the list is
prefixed with a "!", the test is inverted. Some valid values
are "ether", "loopback", "wlan", "wwan". Valid types are named
either from the udev "DEVTYPE" attribute, or "ARPHRD_" macros
in linux/if_arp.h, so this is not comprehensive.
Added in version 211.
Kind=
A whitespace-separated list of shell-style globs matching the
device kind, as exposed by networkctl status INTERFACE or ip
-d link show INTERFACE. If the list is prefixed with a "!",
the test is inverted. Some valid values are "bond", "bridge",
"gre", "tun", "veth". Valid kinds are given by netlink's
"IFLA_INFO_KIND" attribute, so this is not comprehensive.
Added in version 251.
Property=
A whitespace-separated list of udev property names with their
values after equals sign ("="). If multiple properties are
specified, the test results are ANDed. If the list is prefixed
with a "!", the test is inverted. If a value contains white
spaces, then please quote whole key and value pair. If a value
contains quotation, then please escape the quotation with "\".
Example: if a .link file has the following:
Property=ID_MODEL_ID=9999 "ID_VENDOR_FROM_DATABASE=vendor name" "KEY=with \"quotation\""
then, the .link file matches only when an interface has all
the above three properties.
Added in version 243.
Name=
A whitespace-separated list of shell-style globs matching the
device name, as exposed by the udev property "INTERFACE", or
device's alternative names. If the list is prefixed with a
"!", the test is inverted.
Added in version 211.
WLANInterfaceType=
A whitespace-separated list of wireless network type.
Supported values are "ad-hoc", "station", "ap", "ap-vlan",
"wds", "monitor", "mesh-point", "p2p-client", "p2p-go",
"p2p-device", "ocb", and "nan". If the list is prefixed with a
"!", the test is inverted.
Added in version 244.
SSID=
A whitespace-separated list of shell-style globs matching the
SSID of the currently connected wireless LAN. If the list is
prefixed with a "!", the test is inverted.
Added in version 244.
BSSID=
A whitespace-separated list of hardware address of the
currently connected wireless LAN. Use full colon-, hyphen- or
dot-delimited hexadecimal. See the example in MACAddress=.
This option may appear more than once, in which case the lists
are merged. If the empty string is assigned to this option,
the list is reset.
Added in version 244.
Host=
Matches against the hostname or machine ID of the host. See
ConditionHost= in systemd.unit(5) for details. When prefixed
with an exclamation mark ("!"), the result is negated. If an
empty string is assigned, the previously assigned value is
cleared.
Added in version 211.
Virtualization=
Checks whether the system is executed in a virtualized
environment and optionally test whether it is a specific
implementation. See ConditionVirtualization= in
systemd.unit(5) for details. When prefixed with an exclamation
mark ("!"), the result is negated. If an empty string is
assigned, the previously assigned value is cleared.
Added in version 211.
KernelCommandLine=
Checks whether a specific kernel command line option is set.
See ConditionKernelCommandLine= in systemd.unit(5) for
details. When prefixed with an exclamation mark ("!"), the
result is negated. If an empty string is assigned, the
previously assigned value is cleared.
Added in version 211.
KernelVersion=
Checks whether the kernel version (as reported by uname -r)
matches a certain expression. See ConditionKernelVersion= in
systemd.unit(5) for details. When prefixed with an exclamation
mark ("!"), the result is negated. If an empty string is
assigned, the previously assigned value is cleared.
Added in version 237.
Credential=
Checks whether the specified credential was passed to the
systemd-udevd.service service. See System and Service
Credentials[2] for details. When prefixed with an exclamation
mark ("!"), the result is negated. If an empty string is
assigned, the previously assigned value is cleared.
Added in version 252.
Architecture=
Checks whether the system is running on a specific
architecture. See ConditionArchitecture= in systemd.unit(5)
for details. When prefixed with an exclamation mark ("!"), the
result is negated. If an empty string is assigned, the
previously assigned value is cleared.
Added in version 211.
Firmware=
Checks whether the system is running on a machine with the
specified firmware. See ConditionFirmware= in systemd.unit(5)
for details. When prefixed with an exclamation mark ("!"), the
result is negated. If an empty string is assigned, the
previously assigned value is cleared.
Added in version 249.
The [Link] section accepts the following keys:
MACAddress=
The hardware address to set for the device.
Added in version 218.
MTUBytes=
The maximum transmission unit in bytes to set for the device.
The usual suffixes K, M, G, are supported and are understood
to the base of 1024.
Note that if IPv6 is enabled on the interface, and the MTU is
chosen below 1280 (the minimum MTU for IPv6) it will
automatically be increased to this value.
Added in version 218.
ARP=
Takes a boolean. If set to true, the IPv4 ARP (low-level
Address Resolution Protocol) and IPv6 NDP (Neighbor Discovery
Protocol) for this interface are enabled. When unset, the
kernel's default will be used.
For example, disabling ARP is useful when creating multiple
MACVLAN or VLAN virtual interfaces atop a single lower-level
physical interface, which will then only serve as a
link/"bridge" device aggregating traffic to the same physical
link and not participate in the network otherwise. Defaults to
unset.
Added in version 232.
Multicast=
Takes a boolean. If set to true, the multicast flag on the
device is enabled. Defaults to unset.
Added in version 239.
AllMulticast=
Takes a boolean. If set to true, the driver retrieves all
multicast packets from the network. This happens when
multicast routing is enabled. Defaults to unset.
Added in version 239.
Promiscuous=
Takes a boolean. If set to true, promiscuous mode of the
interface is enabled. Defaults to unset.
If this is set to false for the underlying link of a
"passthru" mode MACVLAN/MACVTAP, the virtual interface will be
created with the "nopromisc" flag set.
Added in version 248.
Unmanaged=
Takes a boolean. When "yes", no attempts are made to bring up
or configure matching links, equivalent to when there are no
matching network files. Defaults to "no".
This is useful for preventing later matching network files
from interfering with certain interfaces that are fully
controlled by other applications.
Added in version 233.
Group=
Link groups are similar to port ranges found in managed
switches. When network interfaces are added to a numbered
group, operations on all the interfaces from that group can be
performed at once. Takes an unsigned integer in the range
0...2147483647. Defaults to unset.
Added in version 246.
RequiredForOnline=
Takes a boolean, a minimum operational state (e.g.,
"carrier"), or a range of operational state separated with a
colon (e.g., "degraded:routable"). Please see networkctl(1)
for possible operational states. When "yes", the network is
deemed required when determining whether the system is online
(including when running systemd-networkd-wait-online). When
"no", the network is ignored when determining the online
state. When a minimum operational state and an optional
maximum operational state are set,
systemd-networkd-wait-online deems that the interface is
online when the operational state is in the specified range.
Defaults to "yes" when ActivationPolicy= is not set, or set to
"up", "always-up", or "bound". Defaults to "no" when
ActivationPolicy= is set to "manual" or "down". This is forced
to "no" when ActivationPolicy= is set to "always-down".
The network will be brought up normally (as configured by
ActivationPolicy=), but in the event that there is no address
being assigned by DHCP or the cable is not plugged in, the
link will simply remain offline and be skipped automatically
by systemd-networkd-wait-online if "RequiredForOnline=no".
The boolean value "yes" is translated as follows;
CAN devices
"carrier",
Added in version 256.
Master devices, e.g. bond or bridge
"degraded-carrier" with RequiredFamilyForOnline=any,
Added in version 256.
Bonding port interfaces
"enslaved",
Added in version 256.
Other interfaces
"degraded".
Added in version 236.
This setting can be overridden by the command line option for
systemd-networkd-wait-online. See
systemd-networkd-wait-online.service(8) for more details.
Added in version 236.
RequiredFamilyForOnline=
Takes an address family. When specified, an IP address in the
given family is deemed required when determining whether the
link is online (including when running
systemd-networkd-wait-online). Takes one of "ipv4", "ipv6",
"both", or "any". Defaults to "no". Note that this option has
no effect if "RequiredForOnline=no".
Added in version 249.
ActivationPolicy=
Specifies the policy for systemd-networkd managing the link
administrative state. Specifically, this controls how
systemd-networkd changes the network device's "IFF_UP" flag,
which is sometimes controlled by system administrators by
running e.g., ip link set dev eth0 up or ip link set dev eth0
down, and can also be changed with networkctl up eth0 or
networkctl down eth0.
Takes one of "up", "always-up", "manual", "always-down",
"down", or "bound". When "manual", systemd-networkd will not
change the link's admin state automatically; the system
administrator must bring the interface up or down manually, as
desired. When "up" (the default) or "always-up", or "down" or
"always-down", systemd-networkd will set the link up or down,
respectively, when the interface is (re)configured. When
"always-up" or "always-down", systemd-networkd will set the
link up or down, respectively, any time systemd-networkd
detects a change in the administrative state. When
BindCarrier= is also set, this is automatically set to "bound"
and any other value is ignored.
When the policy is set to "down" or "manual", the default
value of RequiredForOnline= is "no". When the policy is set to
"always-down", the value of RequiredForOnline= forced to "no".
The administrative state is not the same as the carrier state,
so using "always-up" does not mean the link will never lose
carrier. The link carrier depends on both the administrative
state as well as the network device's physical connection.
However, to avoid reconfiguration failures, when using
"always-up", IgnoreCarrierLoss= is forced to true.
Added in version 248.
The [SR-IOV] section accepts the following keys. Specify several
[SR-IOV] sections to configure several SR-IOVs. SR-IOV provides
the ability to partition a single physical PCI resource into
virtual PCI functions which can then be injected into a VM. In the
case of network VFs, SR-IOV improves north-south network
performance (that is, traffic with endpoints outside the host
machine) by allowing traffic to bypass the host machine’s network
stack.
VirtualFunction=
Specifies a Virtual Function (VF), lightweight PCIe function
designed solely to move data in and out. Takes an integer in
the range 0...2147483646. This option is compulsory.
Added in version 251.
VLANId=
Specifies VLAN ID of the virtual function. Takes an integer in
the range 1...4095.
Added in version 251.
QualityOfService=
Specifies quality of service of the virtual function. Takes an
integer in the range 1...4294967294.
Added in version 251.
VLANProtocol=
Specifies VLAN protocol of the virtual function. Takes
"802.1Q" or "802.1ad".
Added in version 251.
MACSpoofCheck=
Takes a boolean. Controls the MAC spoof checking. When unset,
the kernel's default will be used.
Added in version 251.
QueryReceiveSideScaling=
Takes a boolean. Toggle the ability of querying the receive
side scaling (RSS) configuration of the virtual function (VF).
The VF RSS information like RSS hash key may be considered
sensitive on some devices where this information is shared
between VF and the physical function (PF). When unset, the
kernel's default will be used.
Added in version 251.
Trust=
Takes a boolean. Allows one to set trust mode of the virtual
function (VF). When set, VF users can set a specific feature
which may impact security and/or performance. When unset, the
kernel's default will be used.
Added in version 251.
LinkState=
Allows one to set the link state of the virtual function (VF).
Takes a boolean or a special value "auto". Setting to "auto"
means a reflection of the physical function (PF) link state,
"yes" lets the VF to communicate with other VFs on this host
even if the PF link state is down, "no" causes the hardware to
drop any packets sent by the VF. When unset, the kernel's
default will be used.
Added in version 251.
MACAddress=
Specifies the MAC address for the virtual function.
Added in version 251.
The [Network] section accepts the following keys:
Description=
A description of the device. This is only used for
presentation purposes.
Added in version 211.
DHCP=
Enables DHCPv4 and/or DHCPv6 client support. Accepts "yes",
"no", "ipv4", or "ipv6". Defaults to "no".
Note that DHCPv6 will by default be triggered by Router
Advertisements, if reception is enabled, regardless of this
parameter. By explicitly enabling DHCPv6 support here, the
DHCPv6 client will be started in the mode specified by the
WithoutRA= setting in the [DHCPv6] section, regardless of the
presence of routers on the link, or what flags the routers
pass. See IPv6AcceptRA=.
Furthermore, note that by default the domain name specified
through DHCP is not used for name resolution. See option
UseDomains= below.
See the [DHCPv4] or [DHCPv6] sections below for further
configuration options for the DHCP client support.
Added in version 211.
DHCPServer=
Takes a boolean. If set to "yes", DHCPv4 server will be
started. Defaults to "no". Further settings for the DHCP
server may be set in the [DHCPServer] section described below.
Even if this is enabled, the DHCP server will not be started
automatically and wait for the persistent storage being ready
to load/save leases in the storage, unless RelayTarget= or
PersistLeases=no are specified in the [DHCPServer] section. It
will be started after
systemd-networkd-persistent-storage.service is started, which
calls networkctl persistent-storage yes. See networkctl(1) for
more details.
Added in version 215.
LinkLocalAddressing=
Enables link-local address autoconfiguration. Accepts a
boolean, ipv4, and ipv6. An IPv6 link-local address is
configured when yes or ipv6. An IPv4 link-local address is
configured when yes or ipv4 and when DHCPv4 autoconfiguration
has been unsuccessful for some time. (IPv4 link-local address
autoconfiguration will usually happen in parallel with
repeated attempts to acquire a DHCPv4 lease).
Defaults to no when KeepMaster= or Bridge= is set or when the
specified MACVLAN=/MACVTAP= has Mode=passthru, or ipv6
otherwise.
Added in version 219.
IPv6LinkLocalAddressGenerationMode=
Specifies how IPv6 link-local address is generated. Takes one
of "eui64", "none", "stable-privacy" and "random". When unset,
"stable-privacy" is used if IPv6StableSecretAddress= is
specified, and if not, "eui64" is used. Note that if
LinkLocalAddressing= is "no" or "ipv4", then
IPv6LinkLocalAddressGenerationMode= will be ignored. Also,
even if LinkLocalAddressing= is "yes" or "ipv6", setting
IPv6LinkLocalAddressGenerationMode=none disables to configure
an IPv6 link-local address.
Added in version 246.
IPv6StableSecretAddress=
Takes an IPv6 address. The specified address will be used as a
stable secret for generating IPv6 link-local address. If this
setting is specified, and IPv6LinkLocalAddressGenerationMode=
is unset, then
IPv6LinkLocalAddressGenerationMode=stable-privacy is implied.
If this setting is not specified, and "stable-privacy" is set
to IPv6LinkLocalAddressGenerationMode=, then a stable secret
address will be generated from the local machine ID and the
interface name.
Added in version 249.
IPv4LLStartAddress=
Specifies the first IPv4 link-local address to try. Takes an
IPv4 address for example 169.254.1.2, from the link-local
address range: 169.254.0.0/16 except for 169.254.0.0/24 and
169.254.255.0/24. This setting may be useful if the device
should always have the same address as long as there is no
address conflict. When unset, a random address will be
automatically selected. Defaults to unset.
Added in version 252.
IPv4LLRoute=
Takes a boolean. If set to true, sets up the route needed for
non-IPv4LL hosts to communicate with IPv4LL-only hosts.
Defaults to false.
Added in version 216.
DefaultRouteOnDevice=
Takes a boolean. If set to true, sets up the IPv4 default
route bound to the interface. Defaults to false. This is
useful when creating routes on point-to-point interfaces. This
is equivalent to e.g. the following,
ip route add default dev veth99
or,
[Route]
Gateway=0.0.0.0
Currently, there are no way to specify e.g., the table for the
route configured by this setting. To configure the default
route with such an additional property, please use the
following instead:
[Route]
Gateway=0.0.0.0
Table=1234
If you'd like to create an IPv6 default route bound to the
interface, please use the following:
[Route]
Gateway=::
Table=1234
Added in version 243.
LLMNR=
Takes a boolean or "resolve". When true, enables Link-Local
Multicast Name Resolution[3] on the link. When set to
"resolve", only resolution is enabled, but not host
registration and announcement. Defaults to true. This setting
is read by systemd-resolved.service(8).
Added in version 216.
MulticastDNS=
Takes a boolean or "resolve". When true, enables Multicast
DNS[4] support on the link. When set to "resolve", only
resolution is enabled, but not host or service registration
and announcement. Defaults to false. This setting is read by
systemd-resolved.service(8).
Added in version 229.
DNSOverTLS=
Takes a boolean or "opportunistic". When true, enables
DNS-over-TLS[5] support on the link. When set to
"opportunistic", compatibility with non-DNS-over-TLS servers
is increased, by automatically turning off DNS-over-TLS
servers in this case. This option defines a per-interface
setting for resolved.conf(5)'s global DNSOverTLS= option.
Defaults to unset, and the global setting will be used. This
setting is read by systemd-resolved.service(8).
Added in version 239.
DNSSEC=
Takes a boolean or "allow-downgrade". When true, enables
DNSSEC[6] DNS validation support on the link. When set to
"allow-downgrade", compatibility with non-DNSSEC capable
networks is increased, by automatically turning off DNSSEC in
this case. This option defines a per-interface setting for
resolved.conf(5)'s global DNSSEC= option. Defaults to unset,
and the global setting will be used. This setting is read by
systemd-resolved.service(8).
Added in version 229.
DNSSECNegativeTrustAnchors=
A space-separated list of DNSSEC negative trust anchor
domains. If specified and DNSSEC is enabled, look-ups done via
the interface's DNS server will be subject to the list of
negative trust anchors, and not require authentication for the
specified domains, or anything below it. Use this to disable
DNSSEC authentication for specific private domains, that
cannot be proven valid using the Internet DNS hierarchy.
Defaults to the empty list. This setting is read by
systemd-resolved.service(8).
Added in version 229.
LLDP=
Controls support for Ethernet LLDP packet reception. LLDP is a
link-layer protocol commonly implemented on professional
routers and bridges which announces which physical port a
system is connected to, as well as other related data. Accepts
a boolean or the special value "routers-only". When true,
incoming LLDP packets are accepted and a database of all LLDP
neighbors maintained. If "routers-only" is set only LLDP data
of various types of routers is collected and LLDP data about
other types of devices ignored (such as stations, telephones
and others). If false, LLDP reception is disabled. Defaults to
"routers-only". Use networkctl(1) to query the collected
neighbor data. LLDP is only available on Ethernet links. See
EmitLLDP= below for enabling LLDP packet emission from the
local system.
Added in version 219.
EmitLLDP=
Controls support for Ethernet LLDP packet emission. Accepts a
boolean parameter or the special values "nearest-bridge",
"non-tpmr-bridge" and "customer-bridge". Defaults to false,
which turns off LLDP packet emission. If not false, a short
LLDP packet with information about the local system is sent
out in regular intervals on the link. The LLDP packet will
contain information about the local hostname, the local
machine ID (as stored in machine-id(5)) and the local
interface name, as well as the pretty hostname of the system
(as set in machine-info(5)). LLDP emission is only available
on Ethernet links. Note that this setting passes data suitable
for identification of host to the network and should thus not
be enabled on untrusted networks, where such identification
data should not be made available. Use this option to permit
other systems to identify on which interfaces they are
connected to this system. The three special values control
propagation of the LLDP packets. The "nearest-bridge" setting
permits propagation only to the nearest connected bridge,
"non-tpmr-bridge" permits propagation across Two-Port MAC
Relays, but not any other bridges, and "customer-bridge"
permits propagation until a customer bridge is reached. For
details about these concepts, see IEEE 802.1AB-2016[7]. Note
that configuring this setting to true is equivalent to
"nearest-bridge", the recommended and most restricted level of
propagation. See LLDP= above for an option to enable LLDP
reception.
Added in version 230.
BindCarrier=
A link name or a list of link names. When set, controls the
behavior of the current link. When all links in the list are
in an operational down state, the current link is brought
down. When at least one link has carrier, the current
interface is brought up.
This forces ActivationPolicy= to be set to "bound".
Added in version 220.
Address=
A static IPv4 or IPv6 address and its prefix length, separated
by a "/" character. Specify this key more than once to
configure several addresses. The format of the address must be
as described in inet_pton(3). This is a short-hand for an
[Address] section only containing an Address key (see below).
This option may be specified more than once.
If the specified address is "0.0.0.0" (for IPv4) or "::" (for
IPv6), a new address range of the requested size is
automatically allocated from a system-wide pool of unused
ranges. Note that the prefix length must be equal or larger
than 8 for IPv4, and 64 for IPv6. The allocated range is
checked against all current network interfaces and all known
network configuration files to avoid address range conflicts.
The default system-wide pool consists of 192.168.0.0/16,
172.16.0.0/12 and 10.0.0.0/8 for IPv4, and fd00::/8 for IPv6.
This functionality is useful to manage a large number of
dynamically created network interfaces with the same network
configuration and automatic address range assignment.
If an IPv4 link-local address (169.254.0.0/16) is specified,
IPv4 Address Conflict Detection (RFC 5227[8]) is enabled for
the address. To assign an IPv4 link-local address without IPv4
Address Conflict Detection, please use [Address] section to
configure the address and disable DuplicateAddressDetection=.
[Address]
Address=169.254.10.1/24
DuplicateAddressDetection=none
If an empty string is specified, then the all previous
assignments in both [Network] and [Address] sections are
cleared.
Added in version 211.
Gateway=
The gateway address, which must be in the format described in
inet_pton(3). This is a short-hand for a [Route] section only
containing a Gateway= key. This option may be specified more
than once.
Added in version 211.
DNS=
A DNS server address, which must be in the format described in
inet_pton(3). This option may be specified more than once.
Each address can optionally take a port number separated with
":", a network interface name or index separated with "%", and
a Server Name Indication (SNI) separated with "#". When IPv6
address is specified with a port number, then the address must
be in the square brackets. That is, the acceptable full
formats are "111.222.333.444:9953%ifname#example.com" for IPv4
and "[1111:2222::3333]:9953%ifname#example.com" for IPv6. If
an empty string is assigned, then the all previous assignments
are cleared. This setting is read by
systemd-resolved.service(8).
Added in version 211.
UseDomains=
Specifies the protocol-independent default value for the same
settings in [IPv6AcceptRA], [DHCPv4], and [DHCPv6] sections
below. Takes a boolean, or the special value route. See also
the same setting in [DHCPv4] below. Defaults to unset.
Added in version 256.
Domains=
A whitespace-separated list of domains which should be
resolved using the DNS servers on this link. Each item in the
list should be a domain name, optionally prefixed with a tilde
("~"). The domains with the prefix are called "routing-only
domains". The domains without the prefix are called "search
domains" and are first used as search suffixes for extending
single-label hostnames (hostnames containing no dots) to
become fully qualified domain names (FQDNs). If a single-label
hostname is resolved on this interface, each of the specified
search domains are appended to it in turn, converting it into
a fully qualified domain name, until one of them may be
successfully resolved.
Both "search" and "routing-only" domains are used for routing
of DNS queries: look-ups for hostnames ending in those domains
(hence also single label names, if any "search domains" are
listed), are routed to the DNS servers configured for this
interface. The domain routing logic is particularly useful on
multi-homed hosts with DNS servers serving particular private
DNS zones on each interface.
The "routing-only" domain "~." (the tilde indicating
definition of a routing domain, the dot referring to the DNS
root domain which is the implied suffix of all valid DNS
names) has special effect. It causes all DNS traffic which
does not match another configured domain routing entry to be
routed to DNS servers specified for this interface. This
setting is useful to prefer a certain set of DNS servers if a
link on which they are connected is available.
This setting is read by systemd-resolved.service(8). "Search
domains" correspond to the domain and search entries in
resolv.conf(5). Domain name routing has no equivalent in the
traditional glibc API, which has no concept of domain name
servers limited to a specific link.
Added in version 216.
DNSDefaultRoute=
Takes a boolean argument. If true, this link's configured DNS
servers are used for resolving domain names that do not match
any link's configured Domains= setting. If false, this link's
configured DNS servers are never used for such domains, and
are exclusively used for resolving names that match at least
one of the domains configured on this link. If not specified,
defaults to an automatic mode: queries not matching any link's
configured domains will be routed to this link if it has no
routing-only domains configured.
Added in version 240.
NTP=
An NTP server address (either an IP address, or a hostname).
This option may be specified more than once. This setting is
read by systemd-timesyncd.service(8).
Added in version 216.
IPv4Forwarding=
Configures IPv4 packet forwarding for the interface. Takes a
boolean value. This controls the
net.ipv4.conf.INTERFACE.forwarding sysctl option of the
network interface. See IP Sysctl[9] for more details about the
sysctl option. Defaults to true if IPMasquerade= is enabled
for IPv4, otherwise the value specified to the same setting in
networkd.conf(5) will be used. If none of them are specified,
the sysctl option will not be changed.
To control the global setting, use the same setting in
networkd.conf(5).
Added in version 256.
IPv6Forwarding=
Configures interface-specific host/router behaviour. Takes a
boolean value. This controls the
net.ipv6.conf.INTERFACE.forwarding sysctl option of the
network interface. See IP Sysctl[9] for more details about the
sysctl option. Defaults to true if IPMasquerade= is enabled
for IPv6 or IPv6SendRA= is enabled, otherwise the value
specified to the same setting in networkd.conf(5) will be
used. If none of them are specified, the sysctl option will
not be changed.
To control the global setting, use the same setting in
networkd.conf(5).
Note, unlike IPv4Forwarding=, enabling per-interface
IPv6Forwarding= on two or more interfaces DOES NOT make IPv6
packets forwarded within the interfaces. This setting just
controls the per-interface sysctl value, and the sysctl value
is not directly correlated to whether packets are forwarded.
To ensure IPv6 packets forwarded, the global setting in
networkd.conf(5) needs to be enabled.
Added in version 256.
IPMasquerade=
Configures IP masquerading for the network interface. If
enabled, packets forwarded from the network interface will be
appear as coming from the local host. Typically, this should
be enabled on the downstream interface of routers. Takes one
of "ipv4", "ipv6", "both", or "no". Defaults to "no". Note
that any positive boolean values such as "yes" or "true" are
now deprecated. Please use one of the values above. Specifying
"ipv4" or "both" implies IPv4Forwarding= settings in both
.network file for this interface and the global
networkd.conf(5) unless they are explicitly specified.
Similarly for IPv6Forwarding= when "ipv6" or "both" is
specified. See IPv4Forwarding=/IPv6Forwarding= in the above
for the per-link settings, and networkd.conf(5) for the global
settings.
Added in version 219.
IPv6PrivacyExtensions=
Configures use of stateless temporary addresses that change
over time (see RFC 4941[10], Privacy Extensions for Stateless
Address Autoconfiguration in IPv6). Takes a boolean or the
special values "prefer-public" and "kernel". When true,
enables the privacy extensions and prefers temporary addresses
over public addresses. When "prefer-public", enables the
privacy extensions, but prefers public addresses over
temporary addresses. When false, the privacy extensions remain
disabled. When "kernel", the kernel's default setting will be
left in place. When unspecified, the value specified in the
same setting in networkd.conf(5), which defaults to "no", will
be used.
Added in version 222.
IPv6AcceptRA=
Takes a boolean. Controls IPv6 Router Advertisement (RA)
reception support for the interface. If true, RAs are
accepted; if false, RAs are ignored. When RAs are accepted,
they may trigger the start of the DHCPv6 client if the
relevant flags are set in the RA data, or if no routers are
found on the link. Defaults to false for bridge devices, when
IPv6Forwarding=, IPv6SendRA=, or KeepMaster= is enabled.
Otherwise, enabled by default. Cannot be enabled on devices
aggregated in a bond device or when link-local addressing is
disabled.
Further settings for the IPv6 RA support may be configured in
the [IPv6AcceptRA] section, see below.
Also see IP Sysctl[9] in the kernel documentation regarding
"accept_ra", but note that systemd's setting of 1 (i.e. true)
corresponds to kernel's setting of 2.
Note that kernel's implementation of the IPv6 RA protocol is
always disabled, regardless of this setting. If this option is
enabled, a userspace implementation of the IPv6 RA protocol is
used, and the kernel's own implementation remains disabled,
since systemd-networkd needs to know all details supplied in
the advertisements, and these are not available from the
kernel if the kernel's own implementation is used.
Added in version 231.
IPv6DuplicateAddressDetection=
Configures the amount of IPv6 Duplicate Address Detection
(DAD) probes to send. When unset, the kernel's default will be
used.
Added in version 228.
IPv6HopLimit=
Configures IPv6 Hop Limit. Takes an integer in the range
1...255. For each router that forwards the packet, the hop
limit is decremented by 1. When the hop limit field reaches
zero, the packet is discarded. When unset, the kernel's
default will be used.
Added in version 228.
IPv6RetransmissionTimeSec=
Configures IPv6 Retransmission Time. The time between
retransmitted Neighbor Solicitation messages. Used by address
resolution and the Neighbor Unreachability Detection
algorithm. A value of zero is ignored and the kernel's current
value will be used. Defaults to unset, and the kernel's
current value will be used.
Added in version 256.
IPv4ReversePathFilter=
Configure IPv4 Reverse Path Filtering. If enabled, when an
IPv4 packet is received, the machine will first check whether
the source of the packet would be routed through the interface
it came in. If there is no route to the source on that
interface, the machine will drop the packet. Takes one of
"no", "strict", or "loose". When "no", no source validation
will be done. When "strict", each incoming packet is tested
against the FIB and if the incoming interface is not the best
reverse path, the packet check will fail. By default, failed
packets are discarded. When "loose", each incoming packet's
source address is tested against the FIB. The packet is
dropped only if the source address is not reachable via any
interface on that router. See RFC 3704[11]. When unset, the
kernel's default will be used.
Added in version 255.
MulticastIGMPVersion=
Configures IPv4 Multicast IGMP Version to be used, and
controls the value of
/proc/sys/net/ipv4/conf/INTERFACE/force_igmp_version. Takes
one of "no", "v1", "v2", or "v3". When "no", no enforcement of
an IGMP version will be applied, IGMPv1/v2 fallback are
allowed, will back to IGMPv3 mode again if all IGMPv1/v2
Querier Present timer expire. When "v1", use of IGMP version 1
will be enforced, and IGMPv1 report will be replied even if
IGMPv2/v3 queries are received. When "v2", use of IGMP version
2 will be enforced, and IGMPv2 report will be replied if an
IGMPv2/v3 query is received, but fallback to IGMPv1 if an
IGMPv1 query is received. When "v3", use of IGMP version 3
will be enforced, and the same reaction will be done as "no".
Defaults to unset, and the sysctl value will be unchanged.
Added in version 257.
IPv4AcceptLocal=
Takes a boolean. Accept packets with local source addresses.
In combination with suitable routing, this can be used to
direct packets between two local interfaces over the wire and
have them accepted properly. When unset, the kernel's default
will be used.
Added in version 246.
IPv4RouteLocalnet=
Takes a boolean. When true, the kernel does not consider
loopback addresses as martian source or destination while
routing. This enables the use of 127.0.0.0/8 for local routing
purposes. When unset, the kernel's default will be used.
Added in version 248.
IPv4ProxyARP=
Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is
the technique in which one host, usually a router, answers ARP
requests intended for another machine. By "faking" its
identity, the router accepts responsibility for routing
packets to the "real" destination. See RFC 1027[11]. When
unset, the kernel's default will be used.
Added in version 233.
IPv4ProxyARPPrivateVLAN=
Takes a boolean. Configures proxy ARP private VLAN for IPv4,
also known as VLAN aggregation, private VLAN, source-port
filtering, port-isolation, or MAC-forced forwarding.
This variant of the ARP proxy technique will allow the ARP
proxy to reply back to the same interface.
See RFC 3069[12]. When unset, the kernel's default will be
used.
Added in version 256.
IPv6ProxyNDP=
Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP
(Neighbor Discovery Protocol) is a technique for IPv6 to allow
routing of addresses to a different destination when peers
expect them to be present on a certain physical link. In this
case, a router answers Neighbour Advertisement messages
intended for another machine by offering its own MAC address
as destination. Unlike proxy ARP for IPv4, it is not enabled
globally, but will only send Neighbour Advertisement messages
for addresses in the IPv6 neighbor proxy table, which can also
be shown by ip -6 neighbour show proxy. systemd-networkd will
control the per-interface `proxy_ndp` switch for each
configured interface depending on this option. When unset, the
kernel's default will be used.
Added in version 234.
IPv6ProxyNDPAddress=
An IPv6 address, for which Neighbour Advertisement messages
will be proxied. This option may be specified more than once.
systemd-networkd will add the IPv6ProxyNDPAddress= entries to
the kernel's IPv6 neighbor proxy table. This setting implies
IPv6ProxyNDP=yes but has no effect if IPv6ProxyNDP= has been
set to false. When unset, the kernel's default will be used.
Added in version 233.
IPv6SendRA=
Whether to enable or disable Router Advertisement sending on a
link. Takes a boolean value. When enabled, prefixes configured
in [IPv6Prefix] sections and routes configured in the
[IPv6RoutePrefix] sections are distributed as defined in the
[IPv6SendRA] section. If DHCPPrefixDelegation= is enabled,
then the delegated prefixes are also distributed. See
DHCPPrefixDelegation= setting and the [IPv6SendRA],
[IPv6Prefix], [IPv6RoutePrefix], and [DHCPPrefixDelegation]
sections for more configuration options.
If enabled, IPv6Forwarding= on this interface is also enabled,
unless the setting is explicitly specified. See
IPv6Forwarding= in the above for more details.
Added in version 247.
DHCPPrefixDelegation=
Takes a boolean value. When enabled, requests subnet prefixes
on another link via the DHCPv6 protocol or via the 6RD option
in the DHCPv4 protocol. An address within each delegated
prefix will be assigned, and the prefixes will be announced
through IPv6 Router Advertisement if IPv6SendRA= is enabled.
This behaviour can be configured in the [DHCPPrefixDelegation]
section. Defaults to disabled.
Added in version 250.
IPv6MTUBytes=
Configures IPv6 maximum transmission unit (MTU). An integer
greater than or equal to 1280 bytes. When unset, the kernel's
default will be used.
Added in version 239.
MPLSRouting=
Control whether Multi-protocol Label Switching (MPLS) routing
is enabled on this interface. This configures
/proc/sys/net/mpls/conf/INTERFACE/input. Takes a boolean.
Defaults to unset, and the kernel's default will be used.
Note, systemd-networkd does not load any required kernel
modules for MPLS. To enable the feature, mpls_router kernel
module must be loaded before systemd-networkd.service is
started. Consider adding the kernel module to
modules-load.d(5).
Added in version 258.
KeepMaster=
Takes a boolean value. When enabled, the current master
interface index will not be changed, and BatmanAdvanced=,
Bond=, Bridge=, and VRF= settings are ignored. This may be
useful when a netdev with a master interface is created by
another program, e.g. systemd-nspawn(1). Defaults to false.
Added in version 250.
BatmanAdvanced=, Bond=, Bridge=, VRF=
The name of the B.A.T.M.A.N. Advanced, bond, bridge, or VRF
interface to add the link to. See systemd.netdev(5).
Added in version 211.
IPoIB=, IPVLAN=, IPVTAP=, MACsec=, MACVLAN=, MACVTAP=, Tunnel=,
VLAN=, VXLAN=, Xfrm=
The name of an IPoIB, IPVLAN, IPVTAP, MACsec, MACVLAN,
MACVTAP, tunnel, VLAN, VXLAN, or Xfrm to be created on the
link. See systemd.netdev(5). This option may be specified more
than once.
Added in version 211.
ActiveSlave=
Takes a boolean. Specifies the new active slave. The
"ActiveSlave=" option is only valid for following modes:
"active-backup", "balance-alb", and "balance-tlb". Defaults to
false.
Added in version 235.
PrimarySlave=
Takes a boolean. Specifies which slave is the primary device.
The specified device will always be the active slave while it
is available. Only when the primary is off-line will alternate
devices be used. This is useful when one slave is preferred
over another, e.g. when one slave has higher throughput than
another. The "PrimarySlave=" option is only valid for
following modes: "active-backup", "balance-alb", and
"balance-tlb". Defaults to false.
Added in version 235.
ConfigureWithoutCarrier=
Takes a boolean. Allows systemd-networkd to configure a
specific link even if it has no carrier. Defaults to false. If
enabled, and the IgnoreCarrierLoss= setting is not explicitly
set, then it is enabled as well.
With this enabled, to make the interface enter the
"configured" state, which is required to make
systemd-networkd-wait-online work properly for the interface,
all dynamic address configuration mechanisms like DHCP= and
IPv6AcceptRA= (which is enabled by default in most cases) need
to be disabled. Also, DuplicateAddressDetection= (which is
enabled by default for IPv4 link-local addresses and all IPv6
addresses) needs to be disabled for all static address
configurations. Otherwise, without carrier, the interface will
be stuck in the "configuring" state, and
systemd-networkd-wait-online for the interface will timeout.
Also, it is recommended to set RequiredForOnline=no-carrier to
make systemd-networkd-wait-online work for the interface.
Added in version 235.
IgnoreCarrierLoss=
Takes a boolean or a timespan. When true, systemd-networkd
retains both the static and dynamic configuration of the
interface even if its carrier is lost. When false,
systemd-networkd drops both the static and dynamic
configuration of the interface. When a timespan is specified,
systemd-networkd waits for the specified timespan, and ignores
the carrier loss if the link regain its carrier within the
timespan. Setting 0 seconds is equivalent to "no", and
"infinite" is equivalent to "yes".
Setting a finite timespan may be useful when e.g. in the
following cases:
• A wireless interface connecting to a network which has
multiple access points with the same SSID.
• Enslaving a wireless interface to a bond interface, which
may disconnect from the connected access point and causes
its carrier to be lost.
• The driver of the interface resets when the MTU is
changed.
When Bond= is specified to a wireless interface, defaults to 3
seconds. When the DHCPv4 client is enabled and UseMTU= in the
[DHCPv4] section enabled, defaults to 5 seconds. Otherwise,
defaults to the value specified with ConfigureWithoutCarrier=.
When ActivationPolicy= is set to "always-up", this is forced
to "yes", and ignored any user specified values.
Added in version 242.
KeepConfiguration=
Takes a boolean or one of "static", "dynamic-on-stop", and
"dynamic". When "static", systemd-networkd will not drop
statically configured addresses and routes on starting up
process. When "dynamic-on-stop", the dynamically configurad
addresses and routes, such as DHCPv4, DHCPv6, SLAAC, and IPv4
link-local address, will not be dropped when systemd-networkd
is being stopped. When "dynamic", the dynamically configured
addresses and routes will never be dropped, and the lifetime
of DHCPv4 leases will be ignored. This is contrary to the DHCP
specification, but may be the best choice if, e.g., the root
filesystem relies on this connection. The setting "dynamic"
implies "dynamic-on-stop", and "yes" implies "dynamic" and
"static". Defaults to "dynamic-on-stop" when systemd-networkd
is running in initrd, "yes" when the root filesystem is a
network filesystem, and "no" otherwise.
Added in version 257.
An [Address] section accepts the following keys. Specify several
[Address] sections to configure several addresses.
Address=
As in the [Network] section. This setting is mandatory. Each
[Address] section can contain one Address= setting.
Added in version 211.
Peer=
The peer address in a point-to-point connection. Accepts the
same format as the Address= setting.
Added in version 216.
Broadcast=
Takes an IPv4 address or boolean value. The address must be in
the format described in inet_pton(3). If set to true, then the
IPv4 broadcast address will be derived from the Address=
setting. If set to false, then the broadcast address will not
be set. Defaults to true, except for wireguard interfaces,
where it default to false.
Added in version 211.
Label=
Specifies the label for the IPv4 address. The label must be a
7-bit ASCII string with a length of 1...15 characters.
Defaults to unset.
Added in version 211.
PreferredLifetime=
Allows the default "preferred lifetime" of the address to be
overridden. Only three settings are accepted: "forever",
"infinity", which is the default and means that the address
never expires, and "0", which means that the address is
considered immediately "expired" and will not be used, unless
explicitly requested. A setting of PreferredLifetime=0 is
useful for addresses which are added to be used only by a
specific application, which is then configured to use them
explicitly.
Added in version 230.
Scope=
The scope of the address, which can be "global" (valid
everywhere on the network, even through a gateway), "link"
(only valid on this device, will not traverse a gateway) or
"host" (only valid within the device itself, e.g. 127.0.0.1)
or an integer in the range 0...255. Defaults to "global". IPv4
only - IPv6 scope is automatically assigned by the kernel and
cannot be set manually.
Added in version 235.
RouteMetric=
The metric of the prefix route, which is pointing to the
subnet of the configured IP address, taking the configured
prefix length into account. Takes an unsigned integer in the
range 0...4294967295. When unset or set to 0, the kernel's
default value is used. This setting will be ignored when
AddPrefixRoute= is false.
Added in version 246.
HomeAddress=
Takes a boolean. Designates this address the "home address" as
defined in RFC 6275[13]. Supported only on IPv6. Defaults to
false.
Added in version 232.
DuplicateAddressDetection=
Takes one of "ipv4", "ipv6", "both", or "none". When "ipv4",
performs IPv4 Address Conflict Detection. See RFC 5227[8].
When "ipv6", performs IPv6 Duplicate Address Detection. See
RFC 4862[14]. Defaults to "ipv4" for IPv4 link-local addresses
(169.254.0.0/16), "ipv6" for IPv6 addresses, and "none"
otherwise.
Added in version 232.
ManageTemporaryAddress=
Takes a boolean. If true the kernel manage temporary addresses
created from this one as template on behalf of Privacy
Extensions RFC 3041[15]. For this to become active, the
use_tempaddr sysctl setting has to be set to a value greater
than zero. The given address needs to have a prefix length of
64. This flag allows using privacy extensions in a manually
configured network, just like if stateless auto-configuration
was active. Defaults to false.
Added in version 232.
AddPrefixRoute=
Takes a boolean. When true, the prefix route for the address
is automatically added. Defaults to true.
Added in version 245.
AutoJoin=
Takes a boolean. Joining multicast group on ethernet level via
ip maddr command would not work if we have an Ethernet switch
that does IGMP snooping since the switch would not replicate
multicast packets on ports that did not have IGMP reports for
the multicast addresses. Linux vxlan interfaces created via ip
link add vxlan or systemd-networkd's netdev kind vxlan have
the group option that enables them to do the required join. By
extending ip address command with option "autojoin" we can get
similar functionality for openvswitch (OVS) vxlan interfaces
as well as other tunneling mechanisms that need to receive
multicast traffic. Defaults to "no".
Added in version 232.
NetLabel=label
This setting provides a method for integrating static and
dynamic network configuration into Linux NetLabel[16]
subsystem rules, used by Linux Security Modules (LSMs)[17] for
network access control. The label, with suitable LSM rules,
can be used to control connectivity of (for example) a service
with peers in the local network. At least with SELinux, only
the ingress can be controlled but not egress. The benefit of
using this setting is that it may be possible to apply
interface independent part of NetLabel configuration at very
early stage of system boot sequence, at the time when the
network interfaces are not available yet, with netlabelctl(8),
and the per-interface configuration with systemd-networkd once
the interfaces appear later. Currently this feature is only
implemented for SELinux.
The option expects a single NetLabel label. The label must
conform to lexical restrictions of LSM labels. When an
interface is configured with IP addresses, the addresses and
subnetwork masks will be appended to the NetLabel Fallback
Peer Labeling[18] rules. They will be removed when the
interface is deconfigured. Failures to manage the labels will
be ignored.
Warning
Once labeling is enabled for network traffic, a lot of LSM
access control points in Linux networking stack go from
dormant to active. Care should be taken to avoid getting
into a situation where for example remote connectivity is
broken, when the security policy has not been updated to
consider LSM per-packet access controls and no rules would
allow any network traffic. Also note that additional
configuration with netlabelctl(8) is needed.
Example:
[Address]
NetLabel=system_u:object_r:localnet_peer_t:s0
With the example rules applying for interface "eth0", when the
interface is configured with an IPv4 address of 10.0.0.123/8,
systemd-networkd performs the equivalent of netlabelctl
operation
netlabelctl unlbl add interface eth0 address:10.0.0.0/8 label:system_u:object_r:localnet_peer_t:s0
and the reverse operation when the IPv4 address is
deconfigured. The configuration can be used with LSM rules; in
case of SELinux to allow a SELinux domain to receive data from
objects of SELinux "peer" class. For example:
type localnet_peer_t;
allow my_server_t localnet_peer_t:peer recv;
The effect of the above configuration and rules (in absence of
other rules as may be the case) is to only allow "my_server_t"
(and nothing else) to receive data from local subnet
10.0.0.0/8 of interface "eth0".
Added in version 252.
NFTSet=source:family:table:set
This setting provides a method for integrating network
configuration into firewall rules with NFT[19] sets. The
benefit of using the setting is that static network
configuration (or dynamically obtained network addresses, see
similar directives in other sections) can be used in firewall
rules with the indirection of NFT set types. For example,
access could be granted for hosts in the local subnetwork
only. Firewall rules using IP address of an interface are also
instantly updated when the network configuration changes, for
example via DHCP.
This option expects a whitespace separated list of NFT set
definitions. Each definition consists of a colon-separated
tuple of source type (one of "address", "prefix" or
"ifindex"), NFT address family (one of "arp", "bridge",
"inet", "ip", "ip6", or "netdev"), table name and set name.
The names of tables and sets must conform to lexical
restrictions of NFT table names. The type of the element used
in the NFT filter must match the type implied by the directive
("address", "prefix" or "ifindex") and address type (IPv4 or
IPv6) as shown in the table below.
Table 1. Defined source type values
┌─────────────┬─────────────────┬───────────────────┐
│ Source type │ Description │ Corresponding NFT │
│ │ │ type name │
├─────────────┼─────────────────┼───────────────────┤
│ "address" │ host IP address │ "ipv4_addr" or │
│ │ │ "ipv6_addr" │
├─────────────┼─────────────────┼───────────────────┤
│ "prefix" │ network prefix │ "ipv4_addr" or │
│ │ │ "ipv6_addr", with │
│ │ │ "flags interval" │
├─────────────┼─────────────────┼───────────────────┤
│ "ifindex" │ interface index │ "iface_index" │
└─────────────┴─────────────────┴───────────────────┘
When an interface is configured with IP addresses, the
addresses, subnetwork masks or interface index will be
appended to the NFT sets. The information will be removed when
the interface is deconfigured. systemd-networkd only inserts
elements to (or removes from) the sets, so the related NFT
rules, tables and sets must be prepared elsewhere in advance.
Failures to manage the sets will be ignored.
Example:
[Address]
NFTSet=prefix:netdev:filter:eth_ipv4_prefix
Corresponding NFT rules:
table netdev filter {
set eth_ipv4_prefix {
type ipv4_addr
flags interval
}
chain eth_ingress {
type filter hook ingress device "eth0" priority filter; policy drop;
ip daddr != @eth_ipv4_prefix drop
accept
}
}
Added in version 255.
A [Neighbor] section accepts the following keys. The neighbor
section adds a permanent, static entry to the neighbor table
(IPv6) or ARP table (IPv4) for the given hardware address on the
links matched for the network. Specify several [Neighbor] sections
to configure several static neighbors.
Address=
The IP address of the neighbor.
Added in version 240.
LinkLayerAddress=
The link layer address (MAC address or IP address) of the
neighbor.
Added in version 243.
An [IPv6AddressLabel] section accepts the following keys. Specify
several [IPv6AddressLabel] sections to configure several address
labels. IPv6 address labels are used for address selection. See
RFC 3484[20]. Precedence is managed by userspace, and only the
label itself is stored in the kernel.
Label=
The label for the prefix. Takes an unsigned integer in the
range 0...4294967294 (0xfffffffe). 4294967295 (0xffffffff) is
reserved. This setting is mandatory.
Added in version 234.
Prefix=
Takes an IPv6 address with a prefix length, separated by a
slash "/" character. This setting is mandatory.
Added in version 234.
An [RoutingPolicyRule] section accepts the following settings.
Specify several [RoutingPolicyRule] sections to configure several
rules.
TypeOfService=
This specifies the Type of Service (ToS) field of packets to
match; it takes an unsigned integer in the range 0...255. The
field can be used to specify precedence (the first 3 bits) and
ToS (the next 3 bits). The field can be also used to specify
Differentiated Services Code Point (DSCP) (the first 6 bits)
and Explicit Congestion Notification (ECN) (the last 2 bits).
See Type of Service[21] and Differentiated services[22] for
more details.
Added in version 235.
From=
Specifies the source address prefix to match. Possibly
followed by a slash and the prefix length.
Added in version 235.
To=
Specifies the destination address prefix to match. Possibly
followed by a slash and the prefix length.
Added in version 235.
FirewallMark=
Specifies the iptables firewall mark value to match (a number
in the range 1...4294967295). Optionally, the firewall mask
(also a number between 1...4294967295) can be suffixed with a
slash ("/"), e.g., "7/255".
Added in version 235.
Table=
Specifies the routing table identifier to look up if the rule
selector matches. Takes one of predefined names "default",
"main", and "local", and names defined in RouteTable= in
networkd.conf(5), or a number between 1 and 4294967295.
Defaults to "main". Ignored if L3MasterDevice= is true.
Added in version 235.
Priority=
Specifies the priority of this rule. Priority= is an integer
in the range 0...4294967295. Higher number means lower
priority, and rules get processed in order of increasing
number. Defaults to unset, and the kernel will pick a value
dynamically.
Added in version 235.
GoTo=
Specifies the target priority used by "goto" type of rule.
Takes an integer in the range 1...4294967295. This must be
larger than the priority of this rule specified in Priority=.
When specified, Type=goto is implied. This is mandatory when
Type=goto.
Added in version 257.
IncomingInterface=
Specifies incoming device to match. If the interface is
loopback, the rule only matches packets originating from this
host.
Added in version 236.
OutgoingInterface=
Specifies the outgoing device to match. The outgoing interface
is only available for packets originating from local sockets
that are bound to a device.
Added in version 236.
L3MasterDevice=
Takes a boolean. Specifies whether the rule is to direct
lookups to the tables associated with level 3 master devices
(also known as Virtual Routing and Forwarding or VRF devices).
For further details see Virtual Routing and Forwarding
(VRF)[23]. Defaults to false.
Added in version 256.
SourcePort=
Specifies the source IP port or IP port range match in
forwarding information base (FIB) rules. A port range is
specified by the lower and upper port separated by a dash.
Defaults to unset.
Added in version 240.
DestinationPort=
Specifies the destination IP port or IP port range match in
forwarding information base (FIB) rules. A port range is
specified by the lower and upper port separated by a dash.
Defaults to unset.
Added in version 240.
IPProtocol=
Specifies the IP protocol to match in forwarding information
base (FIB) rules. Takes IP protocol name such as "tcp", "udp"
or "sctp", or IP protocol number such as "6" for "tcp" or "17"
for "udp". Defaults to unset.
Added in version 240.
InvertRule=
A boolean. Specifies whether the rule is to be inverted.
Defaults to false.
Added in version 240.
Family=
Takes a special value "ipv4", "ipv6", or "both". By default,
the address family is determined by the address specified in
To= or From=. If neither To= nor From= are specified, then
defaults to "ipv4".
Added in version 243.
User=
Takes a username, a user ID, or a range of user IDs separated
by a dash. Defaults to unset.
Added in version 245.
SuppressPrefixLength=
Takes a number N in the range 0...128 and rejects routing
decisions that have a prefix length of N or less. Defaults to
unset.
Added in version 245.
SuppressInterfaceGroup=
Takes an integer in the range 0...2147483647 and rejects
routing decisions that have an interface with the same group
id. It has the same meaning as suppress_ifgroup in ip rule.
Defaults to unset.
Added in version 250.
Type=
Specifies Routing Policy Database (RPDB) rule type. Takes one
of "table", "goto", "nop", "blackhole", "unreachable", or
"prohibit". When "goto", the target priority must be specified
in GoTo=. Defaults to "table".
Added in version 248.
The [NextHop] section is used to manipulate entries in the
kernel's "nexthop" tables. The [NextHop] section accepts the
following settings. Specify several [NextHop] sections to
configure several hops.
Id=
The id of the next hop. Takes an integer in the range
1...4294967295. This is mandatory if ManageForeignNextHops=no
is specified in networkd.conf(5). Otherwise, if unspecified,
an unused ID will be automatically picked.
Added in version 244.
Gateway=
As in the [Network] section.
Added in version 244.
Family=
Takes one of the special values "ipv4" or "ipv6". By default,
the family is determined by the address specified in Gateway=.
If Gateway= is not specified, then defaults to "ipv4".
Added in version 248.
OnLink=
Takes a boolean. If set to true, the kernel does not have to
check if the gateway is reachable directly by the current
machine (i.e., attached to the local network), so that we can
insert the nexthop in the kernel table without it being
complained about. Defaults to "no".
Added in version 248.
Blackhole=
Takes a boolean. If enabled, packets to the corresponding
routes are discarded silently, and Gateway= cannot be
specified. Defaults to "no".
Added in version 248.
Group=
Takes a whitespace separated list of nexthop IDs. Each ID must
be in the range 1...4294967295. Optionally, each nexthop ID
can take a weight after a colon ("id[:weight]"). The weight
must be in the range 1...255. If the weight is not specified,
then it is assumed that the weight is 1. This setting cannot
be specified with Gateway=, Family=, Blackhole=. This setting
can be specified multiple times. If an empty string is
assigned, then the all previous assignments are cleared.
Defaults to unset.
Added in version 249.
The [Route] section accepts the following settings. Specify
several [Route] sections to configure several routes.
Gateway=
Takes the gateway address or the special values "_dhcp4" and
"_ipv6ra". If "_dhcp4" or "_ipv6ra" is set, then the gateway
address provided by DHCPv4 or IPv6 RA is used.
Added in version 211.
GatewayOnLink=
Takes a boolean. If set to true, the kernel does not have to
check if the gateway is reachable directly by the current
machine (i.e., attached to the local network), so that we can
insert the route in the kernel table without it being
complained about. Defaults to "no".
Added in version 234.
Destination=
The destination prefix of the route. Possibly followed by a
slash and the prefix length. If omitted, a full-length host
route is assumed.
Added in version 211.
Source=
The source prefix of the route. Possibly followed by a slash
and the prefix length. If omitted, a full-length host route is
assumed.
Added in version 218.
Metric=
The metric of the route. Takes an unsigned integer in the
range 0...4294967295. Defaults to unset, and the kernel's
default will be used.
Added in version 216.
IPv6Preference=
Specifies the route preference as defined in RFC 4191[24] for
Router Discovery messages. Which can be one of "low" the route
has a lowest priority, "medium" the route has a default
priority or "high" the route has a highest priority.
Added in version 234.
Scope=
The scope of the IPv4 route, which can be "global", "site",
"link", "host", or "nowhere":
• "global" means the route can reach hosts more than one hop
away.
• "site" means an interior route in the local autonomous
system.
• "link" means the route can only reach hosts on the local
network (one hop away).
• "host" means the route will not leave the local machine
(used for internal addresses like 127.0.0.1).
• "nowhere" means the destination does not exist.
For IPv4 route, defaults to "host" if Type= is "local" or
"nat", and "link" if Type= is "broadcast", "multicast",
"anycast", or "unicast". In other cases, defaults to "global".
The value is not used for IPv6.
Added in version 219.
PreferredSource=
The preferred source address of the route. The address must be
in the format described in inet_pton(3).
Added in version 227.
Table=
The table identifier for the route. Takes one of predefined
names "default", "main", and "local", and names defined in
RouteTable= in networkd.conf(5), or a number between 1 and
4294967295. The table can be retrieved using ip route show
table num. If unset and Type= is "local", "broadcast",
"anycast", or "nat", then "local" is used. In other cases,
defaults to "main".
Added in version 230.
HopLimit=
Configures per route hop limit. Takes an integer in the range
1...255. See also IPv6HopLimit=.
Added in version 255.
Protocol=
The protocol identifier for the route. Takes a number between
0 and 255 or the special values "kernel", "boot", "static",
"ra" and "dhcp". Defaults to "static".
Added in version 234.
Type=
Specifies the type for the route. Takes one of "unicast",
"local", "broadcast", "anycast", "multicast", "blackhole",
"unreachable", "prohibit", "throw", "nat", and "xresolve". If
"unicast", a regular route is defined, i.e. a route indicating
the path to take to a destination network address. If
"blackhole", packets to the defined route are discarded
silently. If "unreachable", packets to the defined route are
discarded and the ICMP message "Host Unreachable" is
generated. If "prohibit", packets to the defined route are
discarded and the ICMP message "Communication Administratively
Prohibited" is generated. If "throw", route lookup in the
current routing table will fail and the route selection
process will return to Routing Policy Database (RPDB).
Defaults to "unicast".
Added in version 235.
InitialCongestionWindow=
The TCP initial congestion window is used during the start of
a TCP connection. During the start of a TCP session, when a
client requests a resource, the server's initial congestion
window determines how many packets will be sent during the
initial burst of data without waiting for acknowledgement.
Takes a number between 1 and 1023. Note that 100 is considered
an extremely large value for this option. When unset, the
kernel's default (typically 10) will be used.
Added in version 237.
InitialAdvertisedReceiveWindow=
The TCP initial advertised receive window is the amount of
receive data (in bytes) that can initially be buffered at one
time on a connection. The sending host can send only that
amount of data before waiting for an acknowledgment and window
update from the receiving host. Takes a number between 1 and
1023. Note that 100 is considered an extremely large value for
this option. When unset, the kernel's default will be used.
Added in version 237.
QuickAck=
Takes a boolean. When true, the TCP quick ACK mode for the
route is enabled. When unset, the kernel's default will be
used.
Added in version 237.
FastOpenNoCookie=
Takes a boolean. When true enables TCP fastopen without a
cookie on a per-route basis. When unset, the kernel's default
will be used.
Added in version 243.
MTUBytes=
The maximum transmission unit in bytes to set for the route.
The usual suffixes K, M, G, are supported and are understood
to the base of 1024.
Added in version 239.
TCPAdvertisedMaximumSegmentSize=
Specifies the Path MSS (in bytes) hints given on TCP layer.
The usual suffixes K, M, G, are supported and are understood
to the base of 1024. An unsigned integer in the range
1...4294967294. When unset, the kernel's default will be used.
Added in version 248.
TCPCongestionControlAlgorithm=
Specifies the TCP congestion control algorithm for the route.
Takes a name of the algorithm, e.g. "bbr", "dctcp", or
"vegas". When unset, the kernel's default will be used.
Added in version 252.
TCPRetransmissionTimeoutSec=
Specifies the TCP Retransmission Timeout (RTO) for the route.
Takes time values in seconds. This value specifies the timeout
of an alive TCP connection, when retransmissions remain
unacknowledged. When unset, the kernel's default will be used.
Added in version 255.
MultiPathRoute=address[@name] [weight]
Configures multipath route. Multipath routing is the technique
of using multiple alternative paths through a network. Takes
gateway address. Optionally, takes a network interface name or
index separated with "@", and a weight in 1..256 for this
multipath route separated with whitespace. This setting can be
specified multiple times. If an empty string is assigned, then
the all previous assignments are cleared.
Added in version 245.
NextHop=
Specifies the nexthop id. Takes an unsigned integer in the
range 1...4294967295. If set, the corresponding [NextHop]
section must be configured. Defaults to unset.
Added in version 248.
The [DHCPv4] section configures the DHCPv4 client, if it is
enabled with the DHCP= setting described above:
RequestAddress=
Takes an IPv4 address. When specified, the Requested IP
Address option (option code 50) is added with it to the
initial DHCPDISCOVER message sent by the DHCP client. Defaults
to unset, and an already assigned dynamic address to the
interface is automatically picked.
Added in version 255.
SendHostname=
When true (the default), the machine's hostname (or the value
specified with Hostname=, described below) will be sent to the
DHCP server. Note that the hostname must consist only of 7-bit
ASCII lower-case characters and no spaces or dots, and be
formatted as a valid DNS domain name. Otherwise, the hostname
is not sent even if this option is true.
Added in version 215.
Hostname=
Use this value for the hostname which is sent to the DHCP
server, instead of machine's hostname. Note that the specified
hostname must consist only of 7-bit ASCII lower-case
characters and no spaces or dots, and be formatted as a valid
DNS domain name.
Added in version 223.
MUDURL=
When configured, the specified Manufacturer Usage Description
(MUD) URL will be sent to the DHCPv4 server. Takes a URL of
length up to 255 characters. A superficial verification that
the string is a valid URL will be performed. DHCPv4 clients
are intended to have at most one MUD URL associated with them.
See RFC 8520[25].
MUD is an embedded software standard defined by the IETF that
allows IoT device makers to advertise device specifications,
including the intended communication patterns for their device
when it connects to the network. The network can then use this
to author a context-specific access policy, so the device
functions only within those parameters.
Added in version 246.
ClientIdentifier=
The DHCPv4 client identifier to use. Takes one of mac or duid.
If set to mac, the MAC address of the link is used. If set to
duid, an RFC4361-compliant Client ID, which is the combination
of IAID and DUID, is used. IAID can be configured by IAID=.
DUID can be configured by DUIDType= and DUIDRawData=. When
Anonymize= is enabled, mac is unconditionally used and the
specified value will be ignored. When unspecified, the value
specified in the same setting in networkd.conf(5) will be
used.
Added in version 220.
VendorClassIdentifier=
The vendor class identifier used to identify vendor type and
configuration.
Added in version 216.
UserClass=
A DHCPv4 client can use UserClass option to identify the type
or category of user or applications it represents. The
information contained in this option is a string that
represents the user class of which the client is a member.
Each class sets an identifying string of information to be
used by the DHCP service to classify clients. Takes a
whitespace-separated list of strings.
Added in version 239.
DUIDType=
Override the global DUIDType= setting for this network. See
networkd.conf(5) for a description of possible values.
Added in version 230.
DUIDRawData=
Override the global DUIDRawData= setting for this network. See
networkd.conf(5) for a description of possible values.
Added in version 230.
IAID=
The DHCP Identity Association Identifier (IAID) for the
interface, a 32-bit unsigned integer.
Added in version 230.
RapidCommit=
Takes a boolean. The DHCPv4 client can obtain configuration
parameters from a DHCPv4 server through a rapid two-message
exchange (discover and ack). When the rapid commit option is
set by both the DHCPv4 client and the DHCPv4 server, the
two-message exchange is used. Otherwise, the four-message
exchange (discover, offer, request, and ack) is used. The
two-message exchange provides faster client configuration. See
RFC 4039[26] for details. Defaults to true when Anonymize=no
and neither AllowList= nor DenyList= is specified, and false
otherwise.
Added in version 255.
Anonymize=
Takes a boolean. When true, the options sent to the DHCP
server will follow the RFC 7844[27] (Anonymity Profiles for
DHCP Clients) to minimize disclosure of identifying
information. Defaults to false.
This option should only be set to true when MACAddressPolicy=
is set to random (see systemd.link(5)).
When true, ClientIdentifier=mac, RapidCommit=no,
SendHostname=no, Use6RD=no, UseCaptivePortal=no, UseMTU=no,
UseNTP=no, UseSIP=no, and UseTimezone=no are implied and these
settings in the .network file are silently ignored. Also,
Hostname=, MUDURL=, RequestAddress=, RequestOptions=,
SendOption=, SendVendorOption=, UserClass=, and
VendorClassIdentifier= are silently ignored.
With this option enabled DHCP requests will mimic those
generated by Microsoft Windows, in order to reduce the ability
to fingerprint and recognize installations. This means DHCP
request sizes will grow and lease data will be more
comprehensive than normally, though most of the requested data
is not actually used.
Added in version 235.
RequestOptions=
Sets request options to be sent to the server in the DHCPv4
request options list. A whitespace-separated list of integers
in the range 1...254. Defaults to unset.
Added in version 244.
SendOption=
Send an arbitrary raw option in the DHCPv4 request. Takes a
DHCP option number, data type and data separated with a colon
("option:type:value"). The option number must be an integer in
the range 1...254. The type takes one of "uint8", "uint16",
"uint32", "ipv4address", or "string". Special characters in
the data string may be escaped using C-style escapes[28]. This
setting can be specified multiple times. If an empty string is
specified, then all options specified earlier are cleared.
Defaults to unset.
Added in version 244.
SendVendorOption=
Send an arbitrary vendor option in the DHCPv4 request. Takes a
DHCP option number, data type and data separated with a colon
("option:type:value"). The option number must be an integer in
the range 1...254. The type takes one of "uint8", "uint16",
"uint32", "ipv4address", or "string". Special characters in
the data string may be escaped using C-style escapes[28]. This
setting can be specified multiple times. If an empty string is
specified, then all options specified earlier are cleared.
Defaults to unset.
Added in version 246.
IPServiceType=
Takes one of the special values "none", "CS6", or "CS4". When
"none" no IP service type is set to the packet sent from the
DHCPv4 client. When "CS6" (network control) or "CS4"
(realtime), the corresponding service type will be set.
Defaults to "CS6".
Added in version 244.
SocketPriority=
The Linux socket option SO_PRIORITY applied to the raw IP
socket used for initial DHCPv4 messages. Unset by default.
Usual values range from 0 to 6. More details about SO_PRIORITY
socket option in socket(7). Can be used in conjunction with
[VLAN] section EgressQOSMaps= setting of .netdev file to set
the 802.1Q VLAN ethernet tagged header priority, see
systemd.netdev(5).
Added in version 253.
Label=
Specifies the label for the IPv4 address received from the
DHCP server. The label must be a 7-bit ASCII string with a
length of 1...15 characters. Defaults to unset.
Added in version 250.
UseDNS=
When true (the default), the DNS servers received from the
DHCP server will be used.
This corresponds to the nameserver option in resolv.conf(5).
Added in version 211.
RoutesToDNS=
When true, the routes to the DNS servers received from the
DHCP server will be configured. When UseDNS= is disabled, this
setting is ignored. Defaults to true.
Added in version 243.
UseNTP=
When true (the default), the NTP servers received from the
DHCP server will be used by systemd-timesyncd.service.
Added in version 220.
RoutesToNTP=
When true, the routes to the NTP servers received from the
DHCP server will be configured. When UseNTP= is disabled, this
setting is ignored. Defaults to true.
Added in version 249.
UseSIP=
When true (the default), the SIP servers received from the
DHCP server will be collected and made available to client
programs.
Added in version 244.
UseCaptivePortal=
When true (the default), the captive portal advertised by the
DHCP server will be recorded and made available to client
programs and displayed in the networkctl(1) status output
per-link.
Added in version 254.
UseDNR=
When true, designated resolvers advertised by the DHCP server
will be used as encrypted DNS servers. See RFC 9463[29].
Defaults to unset, and the value for UseDNS= will be used.
Added in version 257.
UseMTU=
When true, the interface maximum transmission unit from the
DHCP server will be used on the current link. If MTUBytes= is
set, then this setting is ignored. Defaults to false.
Note, some drivers will reset the interfaces if the MTU is
changed. For such interfaces, please try to use
IgnoreCarrierLoss= with a short timespan, e.g. "3 seconds".
Added in version 211.
UseHostname=
When true (the default), the hostname received from the DHCP
server will be set as the transient hostname of the system.
Added in version 211.
UseDomains=
Takes a boolean, or the special value route. When true, the
domain name received from the DHCP server will be used as DNS
search domain over this link, similarly to the effect of the
Domains= setting. If set to route, the domain name received
from the DHCP server will be used for routing DNS queries
only, but not for searching, similarly to the effect of the
Domains= setting when the argument is prefixed with "~".
When unspecified, the value specified in the same setting in
the [Network] section will be used. When it is unspecified,
the value specified in the same setting in the [DHCPv4]
section in networkd.conf(5) will be used. When it is
unspecified, the value specified in the same setting in the
[Network] section in networkd.conf(5) will be used. When none
of them are specified, defaults to "no".
It is recommended to enable this option only on trusted
networks, as setting this affects resolution of all hostnames,
in particular of single-label names. It is generally safer to
use the supplied domain only as routing domain, rather than as
search domain, in order to not have it affect local resolution
of single-label names.
When set to true, this setting corresponds to the domain
option in resolv.conf(5).
Added in version 216.
UseRoutes=
When true (the default), the static routes will be requested
from the DHCP server and added to the routing table with a
metric of 1024, and a scope of global, link or host, depending
on the route's destination and gateway. If the destination is
on the local host, e.g., 127.x.x.x, or the same as the link's
own address, the scope will be set to host. Otherwise, if the
gateway is null (a direct route), a link scope will be used.
For anything else, scope defaults to global.
Added in version 215.
RouteMetric=
Set the routing metric for routes specified by the DHCP server
(including the prefix route added for the specified prefix).
Takes an unsigned integer in the range 0...4294967295.
Defaults to 1024.
Added in version 217.
RouteTable=num
The table identifier for DHCP routes. Takes one of predefined
names "default", "main", and "local", and names defined in
RouteTable= in networkd.conf(5), or a number between
1...4294967295.
When used in combination with VRF=, the VRF's routing table is
used when this parameter is not specified.
Added in version 232.
RouteMTUBytes=
Specifies the MTU for the DHCP routes. Please see the [Route]
section for further details.
Added in version 245.
QuickAck=
Takes a boolean. When true, the TCP quick ACK mode is enabled
for the routes configured by the acquired DHCPv4 lease. When
unset, the kernel's default will be used.
Added in version 253.
InitialCongestionWindow=
As in the [Route] section.
Added in version 255.
InitialAdvertisedReceiveWindow=
As in the [Route] section.
Added in version 255.
UseGateway=
When true, and the DHCP server provides a Router option, the
default gateway based on the router address will be
configured. Defaults to unset, and the value specified with
UseRoutes= will be used.
Note, when the server provides both the Router and Classless
Static Routes option, and UseRoutes= is enabled, the Router
option is always ignored regardless of this setting. See RFC
3442[30].
Added in version 246.
UseTimezone=
When true, the timezone received from the DHCP server will be
set as timezone of the local system. Defaults to false.
Added in version 226.
Use6RD=
When true, subnets of the received IPv6 prefix are assigned to
downstream interfaces which enables DHCPPrefixDelegation=. See
also DHCPPrefixDelegation= in the [Network] section, the
[DHCPPrefixDelegation] section, and RFC 5969[31]. Defaults to
false.
Added in version 250.
UnassignedSubnetPolicy=
Takes "none", or one of the reject types: "unreachable",
"prohibit", "blackhole", or "throw". If a reject type is
specified, the reject route corresponding to the acquired 6RD
prefix will be configured. For example, when "unreachable",
unreachable 2001:db8::/56 dev lo proto dhcp metric 1024 pref medium
will be configured. See RFC 7084[32]. If "none" is specified,
such route will not be configured. This may be useful when
custom firewall rules that handle packets for unassigned
subnets will be configured. Defaults to "unreachable".
Added in version 257.
IPv6OnlyMode=
When true, the DHCPv4 configuration will be delayed by the
timespan provided by the DHCP server and skip to configure
dynamic IPv4 network connectivity if IPv6 connectivity is
provided within the timespan. See RFC 8925[33]. Defaults to
false.
Added in version 255.
FallbackLeaseLifetimeSec=
Allows one to set DHCPv4 lease lifetime when DHCPv4 server
does not send the lease lifetime. Takes one of "forever" or
"infinity". If specified, the acquired address never expires.
Defaults to unset.
Added in version 246.
RequestBroadcast=
Request the server to use broadcast messages before the IP
address has been configured. This is necessary for devices
that cannot receive RAW packets, or that cannot receive
packets at all before an IP address has been configured. On
the other hand, this must not be enabled on networks where
broadcasts are filtered out.
Added in version 216.
MaxAttempts=
Specifies how many times the DHCPv4 client configuration
should be attempted. Takes a number or "infinity". Defaults to
"infinity". Note that the time between retries is increased
exponentially, up to approximately one per minute, so the
network will not be overloaded even if this number is high.
The default is suitable in most circumstances.
Added in version 243.
ListenPort=
Set the port from which the DHCP client packets originate.
Added in version 233.
ServerPort=
Set the port on which the DHCP server is listening.
Added in version 256.
DenyList=
A whitespace-separated list of IPv4 addresses. Each address
can optionally take a prefix length after "/". DHCP offers
from servers in the list are rejected. Note that if AllowList=
is configured then DenyList= is ignored.
Note that this filters only DHCP offers, so the filtering
might not work when RapidCommit= is enabled. See also
RapidCommit= above.
Added in version 246.
AllowList=
A whitespace-separated list of IPv4 addresses. Each address
can optionally take a prefix length after "/". DHCP offers
from servers in the list are accepted.
Note that this filters only DHCP offers, so the filtering
might not work when RapidCommit= is enabled. See also
RapidCommit= in the above.
Added in version 246.
SendRelease=
When true, the DHCPv4 client sends a DHCP release packet when
it stops. Defaults to true.
Added in version 243.
SendDecline=
A boolean. When true, systemd-networkd performs IPv4 Duplicate
Address Detection to the acquired address by the DHCPv4
client. If duplicate is detected, the DHCPv4 client rejects
the address by sending a DHCPDECLINE packet to the DHCP
server, and tries to obtain an IP address again. See RFC
5227[8]. Defaults to false.
Added in version 245.
NetLabel=
This applies the NetLabel for the addresses received with
DHCP, like NetLabel= in [Address] section applies it to
statically configured addresses. See NetLabel= in [Address]
section for more details.
Added in version 252.
NFTSet=
This applies the NFT set for the network configuration
received with DHCP, like NFTSet= in [Address] section applies
it to static configuration. See NFTSet= in [Address] section
for more details. For "address" or "prefix" source types, the
type of the element used in the NFT filter must be
"ipv4_addr".
Added in version 255.
The [DHCPv6] section configures the DHCPv6 client, if it is
enabled with the DHCP= setting described above, or invoked by the
IPv6 Router Advertisement:
MUDURL=, IAID=, DUIDType=, DUIDRawData=, RequestOptions=
As in the [DHCPv4] section.
Added in version 246.
SendOption=
As in the [DHCPv4] section, however because DHCPv6 uses 16-bit
fields to store option numbers, the option number is an
integer in the range 1...65536.
Added in version 246.
SendVendorOption=
Send an arbitrary vendor option in the DHCPv6 request. Takes
an enterprise identifier, DHCP option number, data type, and
data separated with a colon ("enterprise
identifier:option:type:value"). Enterprise identifier is an
unsigned integer in the range 1...4294967294. The option
number must be an integer in the range 1...254. Data type
takes one of "uint8", "uint16", "uint32", "ipv4address",
"ipv6address", or "string". Special characters in the data
string may be escaped using C-style escapes[28]. This setting
can be specified multiple times. If an empty string is
specified, then all options specified earlier are cleared.
Defaults to unset.
Added in version 246.
UserClass=
A DHCPv6 client can use User Class option to identify the type
or category of user or applications it represents. The
information contained in this option is a string that
represents the user class of which the client is a member.
Each class sets an identifying string of information to be
used by the DHCP service to classify clients. Special
characters in the data string may be escaped using C-style
escapes[28]. This setting can be specified multiple times. If
an empty string is specified, then all options specified
earlier are cleared. Takes a whitespace-separated list of
strings. Note that currently NUL bytes are not allowed.
Added in version 246.
VendorClass=
A DHCPv6 client can use VendorClass option to identify the
vendor that manufactured the hardware on which the client is
running. The information contained in the data area of this
option is contained in one or more opaque fields that identify
details of the hardware configuration. Takes a
whitespace-separated list of strings.
Added in version 246.
PrefixDelegationHint=
Takes an IPv6 address with prefix length in the same format as
the Address= in the [Network] section. The DHCPv6 client will
include a prefix hint in the DHCPv6 solicitation sent to the
server. The prefix length must be in the range 1...128.
Defaults to unset.
Added in version 244.
UnassignedSubnetPolicy=
Takes "none" or one of the reject types: "unreachable",
"prohibit", "blackhole", or "throw". If a reject type is
specified, the reject route corresponding to the delegated
prefix will be configured. For example, when "unreachable",
unreachable 2001:db8::/56 dev lo proto dhcp metric 1024 pref medium
will be configured. See RFC 7084[32]. If "none" is specified,
such route will not be configured. This may be useful when
custom firewall rules that handle packets for unassigned
subnets will be configured. Defaults to "unreachable".
Added in version 257.
RapidCommit=
Takes a boolean. The DHCPv6 client can obtain configuration
parameters from a DHCPv6 server through a rapid two-message
exchange (solicit and reply). When the rapid commit option is
set by both the DHCPv6 client and the DHCPv6 server, the
two-message exchange is used. Otherwise, the four-message
exchange (solicit, advertise, request, and reply) is used. The
two-message exchange provides faster client configuration. See
RFC 3315[34] for details. Defaults to true, and the
two-message exchange will be used if the server support it.
Added in version 252.
SendHostname=
When true (the default), the machine's hostname (or the value
specified with Hostname=, described below) will be sent to the
DHCPv6 server. Note that the hostname must consist only of
7-bit ASCII lower-case characters and no spaces or dots, and
be formatted as a valid DNS domain name. Otherwise, the
hostname is not sent even if this option is true.
Added in version 255.
Hostname=
Use this value for the hostname which is sent to the DHCPv6
server, instead of machine's hostname. Note that the specified
hostname must consist only of 7-bit ASCII lower-case
characters and no spaces or dots, and be formatted as a valid
DNS domain name.
Added in version 255.
UseAddress=
When true (the default), the IP addresses provided by the
DHCPv6 server will be assigned.
Added in version 248.
UseCaptivePortal=
When true (the default), the captive portal advertised by the
DHCPv6 server will be recorded and made available to client
programs and displayed in the networkctl(1) status output
per-link.
Added in version 254.
UseDelegatedPrefix=
When true (the default), the client will request the DHCPv6
server to delegate prefixes. If the server provides prefixes
to be delegated, then subnets of the prefixes are assigned to
the interfaces that have DHCPPrefixDelegation=yes. See also
the DHCPPrefixDelegation= setting in the [Network] section,
settings in the [DHCPPrefixDelegation] section, and RFC
8415[35].
Added in version 250.
UseDNS=, UseDNR=, UseNTP=, UseHostname=, UseDomains=, NetLabel=,
SendRelease=
As in the [DHCPv4] section.
Added in version 243.
NFTSet=
This applies the NFT set for the network configuration
received with DHCP, like NFTSet= in [Address] section applies
it to static configuration. See NFTSet= in [Address] section
for more details. For "address" or "prefix" source types, the
type of the element used in the NFT filter must be
"ipv6_addr".
Added in version 255.
WithoutRA=
Allows DHCPv6 client to start without router advertisements's
"managed" or "other configuration" flag. Takes one of "no",
"solicit", or "information-request". If this is not specified,
"solicit" is used when DHCPPrefixDelegation= is enabled and
UplinkInterface=:self is specified in the
[DHCPPrefixDelegation] section. Otherwise, defaults to "no",
and the DHCPv6 client will be started when an RA is received.
See also the DHCPv6Client= setting in the [IPv6AcceptRA]
section.
Added in version 246.
The [DHCPPrefixDelegation] section configures subnet prefixes of
the delegated prefixes acquired by a DHCPv6 client or by a DHCPv4
client through the 6RD option on another interface. The settings
in this section are used only when the DHCPPrefixDelegation=
setting in the [Network] section is enabled.
UplinkInterface=
Specifies the name or the index of the uplink interface, or
one of the special values ":self" and ":auto". When ":self",
the interface itself is considered the uplink interface, and
WithoutRA=solicit is implied if the setting is not explicitly
specified. When ":auto", the first link which acquired
prefixes to be delegated from the DHCPv6 or DHCPv4 server is
selected. Defaults to ":auto".
Added in version 250.
SubnetId=
Configure a specific subnet ID on the interface from a
(previously) received prefix delegation. You can either set
"auto" (the default) or a specific subnet ID (as defined in
RFC 4291[36], section 2.5.4), in which case the allowed value
is hexadecimal, from 0 to 0x7fffffffffffffff inclusive.
Added in version 246.
Announce=
Takes a boolean. When enabled, and IPv6SendRA= in [Network]
section is enabled, the delegated prefixes are distributed
through the IPv6 Router Advertisement. This setting will be
ignored when the DHCPPrefixDelegation= setting is enabled on
the upstream interface. Defaults to yes.
Added in version 247.
Assign=
Takes a boolean. Specifies whether to add an address from the
delegated prefixes which are received from the WAN interface
by the DHCPv6 Prefix Delegation. When true (on LAN interface),
the EUI-64 algorithm will be used by default to form an
interface identifier from the delegated prefixes. See also
Token= setting below. Defaults to yes.
Added in version 246.
Token=
Specifies an optional address generation mode for assigning an
address in each delegated prefix. This accepts the same syntax
as Token= in the [IPv6AcceptRA] section. If Assign= is set to
false, then this setting will be ignored. Defaults to unset,
which means the EUI-64 algorithm will be used.
Added in version 246.
ManageTemporaryAddress=
As in the [Address] section, but defaults to true.
Added in version 248.
RouteMetric=
The metric of the route to the delegated prefix subnet. Takes
an unsigned integer in the range 0...4294967295. When set to
0, the kernel's default value is used. Defaults to 256.
Added in version 249.
NetLabel=
This applies the NetLabel for the addresses received with
DHCP, like NetLabel= in [Address] section applies it to
statically configured addresses. See NetLabel= in [Address]
section for more details.
Added in version 252.
NFTSet=
This applies the NFT set for the network configuration
received with DHCP, like NFTSet= in [Address] section applies
it to static configuration. See NFTSet= in [Address] section
for more details. For "address" or "prefix" source types, the
type of the element used in the NFT filter must be
"ipv6_addr".
Added in version 255.
The [IPv6AcceptRA] section configures the IPv6 Router
Advertisement (RA) client, if it is enabled with the IPv6AcceptRA=
setting described above:
UseRedirect=
When true (the default), Redirect message sent by the current
first-hop router will be accepted, and routes to redirected
nodes will be configured.
Added in version 256.
Token=
Specifies an optional address generation mode for the
Stateless Address Autoconfiguration (SLAAC). The following
values are supported:
eui64
The EUI-64 algorithm will be used to generate an address
for that prefix. Only supported by Ethernet or InfiniBand
interfaces.
Added in version 250.
static:ADDRESS
An IPv6 address must be specified after a colon (":"), and
the lower bits of the supplied address are combined with
the upper bits of a prefix received in a Router
Advertisement (RA) message to form a complete address.
Note that if multiple prefixes are received in an RA
message, or in multiple RA messages, addresses will be
formed from each of them using the supplied address. This
mode implements SLAAC but uses a static interface
identifier instead of an identifier generated by using the
EUI-64 algorithm. Because the interface identifier is
static, if Duplicate Address Detection detects that the
computed address is a duplicate (in use by another node on
the link), then this mode will fail to provide an address
for that prefix. If an IPv6 address without mode is
specified, then "static" mode is assumed.
Added in version 250.
prefixstable[:ADDRESS][,UUID]
The algorithm specified in RFC 7217[37] will be used to
generate interface identifiers. This mode can optionally
take an IPv6 address separated with a colon (":"). If an
IPv6 address is specified, then an interface identifier is
generated only when a prefix received in an RA message
matches the supplied address.
This mode can also optionally take a non-null UUID in the
format which sd_id128_from_string() accepts, e.g.
"86b123b969ba4b7eb8b3d8605123525a" or
"86b123b9-69ba-4b7e-b8b3-d8605123525a". If a UUID is
specified, the value is used as the secret key to generate
interface identifiers. If not specified, then an
application specific ID generated with the system's
machine-ID will be used as the secret key. See
sd-id128(3), sd_id128_from_string(3), and
sd_id128_get_machine(3).
Note that the "prefixstable" algorithm uses both the
interface name and MAC address as input to the hash to
compute the interface identifier, so if either of those
are changed the resulting interface identifier (and
address) will be changed, even if the prefix received in
the RA message has not been changed.
Added in version 250.
If no address generation mode is specified (which is the
default), or a received prefix does not match any of the
addresses provided in "prefixstable" mode, then the EUI-64
algorithm will be used for Ethernet or InfiniBand interfaces,
otherwise "prefixstable" will be used to form an interface
identifier for that prefix.
This setting can be specified multiple times. If an empty
string is assigned, then the all previous assignments are
cleared.
Examples:
Token=eui64
Token=::1a:2b:3c:4d
Token=static:::1a:2b:3c:4d
Token=prefixstable
Token=prefixstable:2002:da8:1::
Added in version 250.
UseDNS=
When true (the default), the DNS servers received in the
Router Advertisement will be used.
This corresponds to the nameserver option in resolv.conf(5).
Added in version 231.
UseDNR=
When true, the DNR servers received in the Router
Advertisement will be used. Defaults to the value of UseDNS=.
Added in version 257.
UseDomains=
Takes a boolean, or the special value "route". When true, the
domain name received via IPv6 Router Advertisement (RA) will
be used as DNS search domain over this link, similarly to the
effect of the Domains= setting. If set to "route", the domain
name received via IPv6 RA will be used for routing DNS queries
only, but not for searching, similarly to the effect of the
Domains= setting when the argument is prefixed with "~".
Defaults to false.
It is recommended to enable this option only on trusted
networks, as setting this affects resolution of all hostnames,
in particular of single-label names. It is generally safer to
use the supplied domain only as routing domain, rather than as
search domain, in order to not have it affect local resolution
of single-label names.
When set to true, this setting corresponds to the domain
option in resolv.conf(5).
Added in version 231.
RouteTable=num
The table identifier for the routes received in the Router
Advertisement. Takes one of predefined names "default",
"main", and "local", and names defined in RouteTable= in
networkd.conf(5), or a number between 1...4294967295.
When used in combination with VRF=, the VRF's routing table is
used when this parameter is not specified.
Added in version 232.
RouteMetric=
Set the routing metric for the routes received in the Router
Advertisement. Takes an unsigned integer in the range
0...4294967295, or three unsigned integer separated with ":",
in that case the first one is used when the router preference
is high, the second is for medium preference, and the last is
for low preference ("high:medium:low"). Defaults to
"512:1024:2048".
Added in version 249.
QuickAck=
Takes a boolean. When true, the TCP quick ACK mode is enabled
for the routes configured by the received RAs. When unset, the
kernel's default will be used.
Added in version 253.
UseMTU=
Takes a boolean. When true, the MTU received in the Router
Advertisement will be used. Defaults to true.
Added in version 250.
UseHopLimit=
Takes a boolean. When true, the hop limit received in the
Router Advertisement will be set to routes configured based on
the advertisement. See also IPv6HopLimit=. Defaults to true.
Added in version 255.
UseReachableTime=
Takes a boolean. When true, the reachable time received in the
Router Advertisement will be set on the interface receiving
the advertisement. It is used as the base timespan of the
validity of a neighbor entry. Defaults to true.
Added in version 256.
UseRetransmissionTime=
Takes a boolean. When true, the retransmission time received
in the Router Advertisement will be set on the interface
receiving the advertisement. It is used as the time between
retransmissions of Neighbor Solicitation messages to a
neighbor when resolving the address or when probing the
reachability of a neighbor. Defaults to true.
Added in version 256.
UseGateway=
When true (the default), the router address will be configured
as the default gateway.
Added in version 250.
UseRoutePrefix=
When true (the default), the routes corresponding to the route
prefixes received in the Router Advertisement will be
configured.
Added in version 250.
UseCaptivePortal=
When true (the default), the captive portal received in the
Router Advertisement will be recorded and made available to
client programs and displayed in the networkctl(1) status
output per-link.
Added in version 254.
UsePREF64=
When true, the IPv6 PREF64 (or NAT64) prefixes received in the
Router Advertisement will be recorded and made available to
client programs and displayed in the networkctl(1) status
output per-link. See RFC 8781[38]. Defaults to false.
Added in version 255.
UseAutonomousPrefix=
When true (the default), the autonomous prefix received in the
Router Advertisement will be used and take precedence over any
statically configured ones.
Added in version 242.
UseOnLinkPrefix=
When true (the default), the onlink prefix received in the
Router Advertisement will be used and takes precedence over
any statically configured ones.
Added in version 242.
RouterDenyList=
A whitespace-separated list of IPv6 router addresses. Each
address can optionally take a prefix length after "/". Any
information advertised by the listed router is ignored.
Added in version 248.
RouterAllowList=
A whitespace-separated list of IPv6 router addresses. Each
address can optionally take a prefix length after "/". Only
information advertised by the listed router is accepted. Note
that if RouterAllowList= is configured then RouterDenyList= is
ignored.
Added in version 248.
PrefixDenyList=
A whitespace-separated list of IPv6 prefixes. Each prefix can
optionally take its prefix length after "/". IPv6 prefixes
supplied via router advertisements in the list are ignored.
Added in version 248.
PrefixAllowList=
A whitespace-separated list of IPv6 prefixes. Each prefix can
optionally take its prefix length after "/". IPv6 prefixes
supplied via router advertisements in the list are allowed.
Note that if PrefixAllowList= is configured then
PrefixDenyList= is ignored.
Added in version 248.
RouteDenyList=
A whitespace-separated list of IPv6 route prefixes. Each
prefix can optionally take its prefix length after "/". IPv6
route prefixes supplied via router advertisements in the list
are ignored.
Added in version 248.
RouteAllowList=
A whitespace-separated list of IPv6 route prefixes. Each
prefix can optionally take its prefix length after "/". IPv6
route prefixes supplied via router advertisements in the list
are allowed. Note that if RouteAllowList= is configured then
RouteDenyList= is ignored.
Added in version 248.
DHCPv6Client=
Takes a boolean, or the special value "always". When true, the
DHCPv6 client will be started in "solicit" mode if the RA has
the "managed" flag or "information-request" mode if the RA
lacks the "managed" flag but has the "other configuration"
flag. If set to "always", the DHCPv6 client will be started in
"solicit" mode when an RA is received, even if neither the
"managed" nor the "other configuration" flag is set in the RA.
This will be ignored when WithoutRA= in the [DHCPv6] section
is enabled, or UplinkInterface=:self in the
[DHCPPrefixDelegation] section is specified. Defaults to true.
Added in version 246.
NetLabel=
This applies the NetLabel for the addresses received with RA,
like NetLabel= in [Address] section applies it to statically
configured addresses. See NetLabel= in [Address] section for
more details.
Added in version 252.
NFTSet=
This applies the NFT set for the network configuration
received with RA, like NFTSet= in [Address] section applies it
to static configuration. See NFTSet= in [Address] section for
more details. For "address" or "prefix" source types, the type
of the element used in the NFT filter must be "ipv6_addr".
Added in version 255.
The [DHCPServer] section contains settings for the DHCP server, if
enabled via the DHCPServer= option described above:
ServerAddress=
Specifies the server address for the DHCP server. Takes an
IPv4 address with prefix length separated with a slash, e.g.
"192.168.0.1/24". Defaults to unset, and one of static IPv4
addresses configured in [Network] or [Address] section will be
automatically selected. This setting may be useful when the
interface on which the DHCP server is running has multiple
static IPv4 addresses.
This implies Address= in [Network] or [Address] section with
the same address and prefix length. That is,
[Network]
DHCPServer=yes
Address=192.168.0.1/24
Address=192.168.0.2/24
[DHCPServer]
ServerAddress=192.168.0.1/24
or
[Network]
DHCPServer=yes
[Address]
Address=192.168.0.1/24
[Address]
Address=192.168.0.2/24
[DHCPServer]
ServerAddress=192.168.0.1/24
are equivalent to the following:
[Network]
DHCPServer=yes
Address=192.168.0.2/24
[DHCPServer]
ServerAddress=192.168.0.1/24
Since version 255, like the Address= setting in [Network] or
[Address] section, this also supports a null address, e.g.
"0.0.0.0/24", and an unused address will be automatically
selected. For more details about the automatic address
selection, see Address= setting in [Network] section in the
above.
Added in version 249.
PoolOffset=, PoolSize=
Configures the pool of addresses to hand out. The pool is a
contiguous sequence of IP addresses in the subnet configured
for the server address, which does not include the subnet nor
the broadcast address. PoolOffset= takes the offset of the
pool from the start of subnet, or zero to use the default
value. PoolSize= takes the number of IP addresses in the pool
or zero to use the default value. By default, the pool starts
at the first address after the subnet address and takes up the
rest of the subnet, excluding the broadcast address. If the
pool includes the server address (the default), this is
reserved and not handed out to clients.
Added in version 226.
DefaultLeaseTimeSec=, MaxLeaseTimeSec=
Control the default and maximum DHCP lease time to pass to
clients. These settings take time values in seconds or another
common time unit, depending on the suffix. The default lease
time is used for clients that did not ask for a specific lease
time. If a client asks for a lease time longer than the
maximum lease time, it is automatically shortened to the
specified time. The default lease time defaults to 1h, the
maximum lease time to 12h. Shorter lease times are beneficial
if the configuration data in DHCP leases changes frequently
and clients shall learn the new settings with shorter
latencies. Longer lease times reduce the generated DHCP
network traffic.
Added in version 226.
UplinkInterface=
Specifies the name or the index of the uplink interface, or
one of the special values ":none" and ":auto". When emitting
DNS, NTP, or SIP servers is enabled but no servers are
specified, the servers configured in the uplink interface will
be emitted. When ":auto", the link which has a default gateway
with the highest priority will be automatically selected. When
":none", no uplink interface will be selected. Defaults to
":auto".
Added in version 249.
EmitDNS=, DNS=
EmitDNS= takes a boolean. Configures whether the DHCP leases
handed out to clients shall contain DNS server information.
Defaults to "yes". The DNS servers to pass to clients may be
configured with the DNS= option, which takes a list of IPv4
addresses, or special value "_server_address" which will be
converted to the address used by the DHCP server.
If the EmitDNS= option is enabled but no servers configured,
the servers are automatically propagated from an "uplink"
interface that has appropriate servers set. The "uplink"
interface is determined by the default route of the system
with the highest priority. Note that this information is
acquired at the time the lease is handed out, and does not
take uplink interfaces into account that acquire DNS server
information at a later point. If no suitable uplink interface
is found the DNS server data from /etc/resolv.conf is used.
Also, note that the leases are not refreshed if the uplink
network configuration changes. To ensure clients regularly
acquire the most current uplink DNS server information, it is
thus advisable to shorten the DHCP lease time via
MaxLeaseTimeSec= described above.
This setting can be specified multiple times. If an empty
string is specified, then all DNS servers specified earlier
are cleared.
Added in version 226.
EmitNTP=, NTP=, EmitSIP=, SIP=, EmitPOP3=, POP3=, EmitSMTP=,
SMTP=, EmitLPR=, LPR=
Similar to the EmitDNS= and DNS= settings described above,
these settings configure whether and what server information
for the indicate protocol shall be emitted as part of the DHCP
lease. The same syntax, propagation semantics and defaults
apply as for EmitDNS= and DNS=.
Added in version 226.
EmitRouter=, Router=
The EmitRouter= setting takes a boolean value, and configures
whether the DHCP lease should contain the router option. The
Router= setting takes an IPv4 address, and configures the
router address to be emitted. When the Router= setting is not
specified, then the server address will be used for the router
option. When the EmitRouter= setting is disabled, the Router=
setting will be ignored. The EmitRouter= setting defaults to
true, and the Router= setting defaults to unset.
Added in version 230.
EmitTimezone=, Timezone=
Takes a boolean. Configures whether the DHCP leases handed out
to clients shall contain timezone information. Defaults to
"yes". The Timezone= setting takes a timezone string (such as
"Europe/Berlin" or "UTC") to pass to clients. If no explicit
timezone is set, the system timezone of the local host is
propagated, as determined by the /etc/localtime symlink.
Added in version 226.
BootServerAddress=
Takes an IPv4 address of the boot server used by e.g. PXE boot
systems. When specified, this address is sent in the siaddr
field of the DHCP message header. See RFC 2131[39] for more
details. Defaults to unset.
Added in version 251.
BootServerName=
Takes a name of the boot server used by e.g. PXE boot systems.
When specified, this name is sent in the DHCP option 66 ("TFTP
server name"). See RFC 2132[40] for more details. Defaults to
unset.
Note that typically setting one of BootServerName= or
BootServerAddress= is sufficient, but both can be set too, if
desired.
Added in version 251.
BootFilename=
Takes a path or URL to a file loaded by e.g. a PXE boot
loader. When specified, this path is sent in the DHCP option
67 ("Bootfile name"). See RFC 2132[40] for more details.
Defaults to unset.
Added in version 251.
IPv6OnlyPreferredSec=
Takes a timespan. Controls the RFC 8925[33] IPv6-Only
Preferred option. Specifies the DHCPv4 option to indicate that
a host supports an IPv6-only mode and is willing to forgo
obtaining an IPv4 address if the network provides IPv6
connectivity. Defaults to unset, and not send the option. The
minimum allowed value is 300 seconds.
Added in version 255.
SendOption=
Send a raw option with value via DHCPv4 server. Takes a DHCP
option number, data type and data ("option:type:value"). The
option number is an integer in the range 1...254. The type
takes one of "uint8", "uint16", "uint32", "ipv4address",
"ipv6address", or "string". Special characters in the data
string may be escaped using C-style escapes[28]. This setting
can be specified multiple times. If an empty string is
specified, then all options specified earlier are cleared.
Defaults to unset.
Added in version 244.
SendVendorOption=
Send a vendor option with value via DHCPv4 server. Takes a
DHCP option number, data type and data ("option:type:value").
The option number is an integer in the range 1...254. The type
takes one of "uint8", "uint16", "uint32", "ipv4address", or
"string". Special characters in the data string may be escaped
using C-style escapes[28]. This setting can be specified
multiple times. If an empty string is specified, then all
options specified earlier are cleared. Defaults to unset.
Added in version 246.
BindToInterface=
Takes a boolean value. When "yes", DHCP server socket will be
bound to its network interface and all socket communication
will be restricted to this interface. Defaults to "yes",
except if RelayTarget= is used (see below), in which case it
defaults to "no".
Added in version 249.
RelayTarget=
Takes an IPv4 address, which must be in the format described
in inet_pton(3). Turns this DHCP server into a DHCP relay
agent. See RFC 1542[41]. The address is the address of DHCP
server or another relay agent to forward DHCP messages to and
from.
Added in version 249.
RelayAgentCircuitId=
Specifies value for Agent Circuit ID suboption of Relay Agent
Information option. Takes a string, which must be in the
format "string:value", where "value" should be replaced with
the value of the suboption. Defaults to unset (means no Agent
Circuit ID suboption is generated). Ignored if RelayTarget= is
not specified.
Added in version 249.
RelayAgentRemoteId=
Specifies value for Agent Remote ID suboption of Relay Agent
Information option. Takes a string, which must be in the
format "string:value", where "value" should be replaced with
the value of the suboption. Defaults to unset (means no Agent
Remote ID suboption is generated). Ignored if RelayTarget= is
not specified.
Added in version 249.
RapidCommit=
Takes a boolean. When true, the server supports RFC 4039[42].
When a client sends a DHCPDISCOVER message with the Rapid
Commit option to the server, then the server will reply with a
DHCPACK message to the client, instead of DHCPOFFER. Defaults
to true.
Added in version 255.
PersistLeases=
Takes a boolean. When true, the DHCP server will load and save
leases in the persistent storage. When false, the DHCP server
will neither load nor save leases in the persistent storage.
Hence, bound leases will be lost when the interface is
reconfigured e.g. by networkctl reconfigure, or
systemd-networkd.service(8) is restarted. That may cause
address conflict on the network. So, please take an extra care
when disable this setting. When unspecified, the value
specified in the same setting in networkd.conf(5), which
defaults to "yes", will be used.
Added in version 256.
The "[DHCPServerStaticLease]" section configures a static DHCP
lease to assign a fixed IPv4 address to a specific device based on
its MAC address. This section can be specified multiple times.
MACAddress=
The hardware address of a device to match. This key is
mandatory.
Added in version 249.
Address=
The IPv4 address that should be assigned to the device that
was matched with MACAddress=. This key is mandatory.
Added in version 249.
The [IPv6SendRA] section contains settings for sending IPv6 Router
Advertisements and whether to act as a router, if enabled via the
IPv6SendRA= option described above. IPv6 network prefixes or
routes are defined with one or more [IPv6Prefix] or
[IPv6RoutePrefix] sections.
Managed=, OtherInformation=
Takes a boolean. Controls whether a DHCPv6 server is used to
acquire IPv6 addresses on the network link when Managed= is
set to "true" or if only additional network information can be
obtained via DHCPv6 for the network link when
OtherInformation= is set to "true". Both settings default to
"false", which means that a DHCPv6 server is not being used.
Added in version 235.
RouterLifetimeSec=
Takes a timespan. Configures the IPv6 router lifetime in
seconds. The value must be 0 seconds, or between 4 seconds and
9000 seconds. When set to 0, the host is not acting as a
router. Defaults to 1800 seconds (30 minutes).
Added in version 235.
ReachableTimeSec=
Configures the time, used in the Neighbor Unreachability
Detection algorithm, for which clients can assume a neighbor
is reachable after having received a reachability
confirmation. Takes a time span in the range 0...4294967295
ms. When 0, clients will handle it as if the value was not
specified. Defaults to 0.
Added in version 256.
RetransmitSec=
Configures the time, used in the Neighbor Unreachability
Detection algorithm, for which clients can use as retransmit
time on address resolution and the Neighbor Unreachability
Detection algorithm. Takes a time span in the range
0...4294967295 ms. When 0, clients will handle it as if the
value wasn't specified. Defaults to 0.
Added in version 255.
RouterPreference=
Configures IPv6 router preference if RouterLifetimeSec= is
non-zero. Valid values are "high", "medium" and "low", with
"normal" and "default" added as synonyms for "medium" just to
make configuration easier. See RFC 4191[24] for details.
Defaults to "medium".
Added in version 235.
HopLimit=
Configures hop limit. Takes an integer in the range 0...255.
See also IPv6HopLimit=.
Added in version 255.
UplinkInterface=
Specifies the name or the index of the uplink interface, or
one of the special values ":none" and ":auto". When emitting
DNS servers or search domains is enabled but no servers are
specified, the servers configured in the uplink interface will
be emitted. When ":auto", the value specified to the same
setting in the [DHCPPrefixDelegation] section will be used if
DHCPPrefixDelegation= is enabled, otherwise the link which has
a default gateway with the highest priority will be
automatically selected. When ":none", no uplink interface will
be selected. Defaults to ":auto".
Added in version 250.
EmitDNS=, DNS=
DNS= specifies a list of recursive DNS server IPv6 addresses
that are distributed via Router Advertisement messages when
EmitDNS= is true. DNS= also takes special value
"_link_local"; in that case the IPv6 link-local address is
distributed. If DNS= is empty, DNS servers are read from the
[Network] section. If the [Network] section does not contain
any DNS servers either, DNS servers from the uplink interface
specified in UplinkInterface= will be used. When EmitDNS= is
false, no DNS server information is sent in Router
Advertisement messages. EmitDNS= defaults to true.
Added in version 235.
EmitDomains=, Domains=
A list of DNS search domains distributed via Router
Advertisement messages when EmitDomains= is true. If Domains=
is empty, DNS search domains are read from the [Network]
section. If the [Network] section does not contain any DNS
search domains either, DNS search domains from the uplink
interface specified in UplinkInterface= will be used. When
EmitDomains= is false, no DNS search domain information is
sent in Router Advertisement messages. EmitDomains= defaults
to true.
Added in version 235.
DNSLifetimeSec=
Lifetime in seconds for the DNS server addresses listed in
DNS= and search domains listed in Domains=. Defaults to 3600
seconds (one hour).
Added in version 235.
HomeAgent=
Takes a boolean. Specifies that IPv6 router advertisements
indicate to hosts that the router acts as a Home Agent and
includes a Home Agent option. Defaults to false. See RFC
6275[13] for further details.
Added in version 255.
HomeAgentLifetimeSec=
Takes a timespan. Specifies the lifetime of the Home Agent. An
integer, the default unit is seconds, in the range 1...65535.
Defaults to the value set to RouterLifetimeSec=.
Added in version 255.
HomeAgentPreference=
Configures IPv6 Home Agent preference. Takes an integer in the
range 0...65535. Defaults to 0.
Added in version 255.
One or more [IPv6Prefix] sections contain the IPv6 prefixes that
are announced via Router Advertisements. See RFC 4861[43] for
further details.
AddressAutoconfiguration=, OnLink=
Takes a boolean to specify whether IPv6 addresses can be
autoconfigured with this prefix and whether the prefix can be
used for onlink determination. Both settings default to "true"
in order to ease configuration.
Added in version 235.
Prefix=
The IPv6 prefix that is to be distributed to hosts. Similarly
to configuring static IPv6 addresses, the setting is
configured as an IPv6 prefix and its prefix length, separated
by a "/" character. Use multiple [IPv6Prefix] sections to
configure multiple IPv6 prefixes since prefix lifetimes,
address autoconfiguration and onlink status may differ from
one prefix to another.
Added in version 235.
PreferredLifetimeSec=, ValidLifetimeSec=
Preferred and valid lifetimes for the prefix measured in
seconds. PreferredLifetimeSec= defaults to 1800 seconds (30
minutes) and ValidLifetimeSec= defaults to 3600 seconds (one
hour).
Added in version 235.
Assign=
Takes a boolean. When true, adds an address from the prefix.
Default to false.
Added in version 246.
Token=
Specifies an optional address generation mode for assigning an
address in each prefix. This accepts the same syntax as Token=
in the [IPv6AcceptRA] section. If Assign= is set to false,
then this setting will be ignored. Defaults to unset, which
means the EUI-64 algorithm will be used.
Added in version 250.
RouteMetric=
The metric of the prefix route. Takes an unsigned integer in
the range 0...4294967295. When unset or set to 0, the kernel's
default value is used. This setting is ignored when Assign= is
false.
Added in version 249.
One or more [IPv6RoutePrefix] sections contain the IPv6 prefix
routes that are announced via Router Advertisements. See RFC
4191[24] for further details.
Route=
The IPv6 route that is to be distributed to hosts. Similarly
to configuring static IPv6 routes, the setting is configured
as an IPv6 prefix routes and its prefix route length,
separated by a "/" character. Use multiple [IPv6RoutePrefix]
sections to configure multiple IPv6 prefix routes.
Added in version 244.
LifetimeSec=
Lifetime for the route prefix measured in seconds.
LifetimeSec= defaults to 3600 seconds (one hour).
Added in version 244.
Preference=
Specifies the preference of the route option. Takes one of
"high", "medium", or "low". Defaults to "medium".
Added in version 258.
One or more [IPv6PREF64Prefix] sections contain the IPv6 PREF64
(or NAT64) prefixes that are announced via Router Advertisements.
See RFC 8781[38] for further details.
Prefix=
The IPv6 PREF64 (or NAT64) prefix that is to be distributed to
hosts. The setting holds an IPv6 prefix that should be set up
for NAT64 translation (PLAT) to allow 464XLAT on the network
segment. Use multiple [IPv6PREF64Prefix] sections to configure
multiple IPv6 prefixes since prefix lifetime may differ from
one prefix to another. The prefix is an address with a prefix
length, separated by a slash "/" character. Valid NAT64 prefix
length are 96, 64, 56, 48, 40, and 32 bits.
Added in version 255.
LifetimeSec=
Lifetime for the prefix measured in seconds. Should be greater
than or equal to RouterLifetimeSec=. LifetimeSec= defaults to
1800 seconds.
Added in version 255.
The [Bridge] section accepts the following keys:
UnicastFlood=
Takes a boolean. Controls whether the bridge should flood
traffic for which an FDB entry is missing and the destination
is unknown through this port. When unset, the kernel's default
will be used.
Added in version 223.
MulticastFlood=
Takes a boolean. Controls whether the bridge should flood
traffic for which an MDB entry is missing and the destination
is unknown through this port. When unset, the kernel's default
will be used.
Added in version 242.
MulticastToUnicast=
Takes a boolean. Multicast to unicast works on top of the
multicast snooping feature of the bridge. Which means unicast
copies are only delivered to hosts which are interested in it.
When unset, the kernel's default will be used.
Added in version 240.
NeighborSuppression=
Takes a boolean. Configures whether ARP and ND neighbor
suppression is enabled for this port. When unset, the kernel's
default will be used.
Added in version 242.
Learning=
Takes a boolean. Configures whether MAC address learning is
enabled for this port. When unset, the kernel's default will
be used.
Added in version 242.
HairPin=
Takes a boolean. Configures whether traffic may be sent back
out of the port on which it was received. When this flag is
false, then the bridge will not forward traffic back out of
the receiving port. When unset, the kernel's default will be
used.
Added in version 223.
Isolated=
Takes a boolean. Configures whether this port is isolated or
not. Within a bridge, isolated ports can only communicate with
non-isolated ports. When set to true, this port can only
communicate with other ports whose Isolated setting is false.
When set to false, this port can communicate with any other
ports. When unset, the kernel's default will be used.
Added in version 251.
UseBPDU=
Takes a boolean. Configures whether STP Bridge Protocol Data
Units will be processed by the bridge port. When unset, the
kernel's default will be used.
Added in version 223.
FastLeave=
Takes a boolean. This flag allows the bridge to immediately
stop multicast traffic on a port that receives an IGMP Leave
message. It is only used with IGMP snooping if enabled on the
bridge. When unset, the kernel's default will be used.
Added in version 223.
AllowPortToBeRoot=
Takes a boolean. Configures whether a given port is allowed to
become a root port. Only used when STP is enabled on the
bridge. When unset, the kernel's default will be used.
Added in version 223.
ProxyARP=
Takes a boolean. Configures whether proxy ARP to be enabled on
this port. When unset, the kernel's default will be used.
Added in version 243.
ProxyARPWiFi=
Takes a boolean. Configures whether proxy ARP to be enabled on
this port which meets extended requirements by IEEE 802.11 and
Hotspot 2.0 specifications. When unset, the kernel's default
will be used.
Added in version 243.
MulticastRouter=
Configures this port for having multicast routers attached. A
port with a multicast router will receive all multicast
traffic. Takes one of "no" to disable multicast routers on
this port, "query" to let the system detect the presence of
routers, "permanent" to permanently enable multicast traffic
forwarding on this port, or "temporary" to enable multicast
routers temporarily on this port, not depending on incoming
queries. When unset, the kernel's default will be used.
Added in version 243.
Cost=
Sets the "cost" of sending packets of this interface. Each
port in a bridge may have a different speed and the cost is
used to decide which link to use. Faster interfaces should
have lower costs. It is an integer value between 1 and 65535.
Added in version 218.
Priority=
Sets the "priority" of sending packets on this interface. Each
port in a bridge may have a different priority which is used
to decide which link to use. Lower value means higher
priority. It is an integer value between 0 to 63.
systemd-networkd does not set any default, meaning the kernel
default value of 32 is used.
Added in version 234.
Locked=, MACAuthenticationBypass=
Takes a boolean. Configures whether the port is "locked" and
does not allow traffic forwarded until fully authenticated,
e.g. via 802.1x. When unset, the kernel's default will be
used.
Added in version 258. Takes a boolean. Configures whether a
locked port has "MAC Authentication Bypass" enabled and
creates newly learned fdb entries in a "locked" state. User
space can authenticate these entries by clearing the locked
flag. Requires Learning to be enabled. When unset, the
kernel's default will be used.
Added in version 258.
The [BridgeFDB] section manages the forwarding database table of a
port and accepts the following keys. Specify several [BridgeFDB]
sections to configure several static MAC table entries.
MACAddress=
As in the [Network] section. This key is mandatory.
Added in version 219.
Destination=
Takes an IP address of the destination VXLAN tunnel endpoint.
Added in version 243.
VLANId=
The VLAN ID for the new static MAC table entry. If omitted, no
VLAN ID information is appended to the new static MAC table
entry.
Added in version 219.
VNI=
The VXLAN Network Identifier (or VXLAN Segment ID) to use to
connect to the remote VXLAN tunnel endpoint. Takes a number in
the range 1...16777215. Defaults to unset.
Added in version 243.
AssociatedWith=
Specifies where the address is associated with. Takes one of
"use", "self", "master" or "router". "use" means the address
is in use. User space can use this option to indicate to the
kernel that the fdb entry is in use. "self" means the address
is associated with the port drivers fdb. Usually hardware.
"master" means the address is associated with master devices
fdb. "router" means the destination address is associated
with a router. Note that it is valid if the referenced device
is a VXLAN type device and has route shortcircuit enabled.
Defaults to "self".
Added in version 243.
OutgoingInterface=
Specifies the name or index of the outgoing interface for the
VXLAN device driver to reach the remote VXLAN tunnel endpoint.
Defaults to unset.
Added in version 249.
The [BridgeMDB] section manages the multicast membership entries
forwarding database table of a port and accepts the following
keys. Specify several [BridgeMDB] sections to configure several
permanent multicast membership entries.
MulticastGroupAddress=
Specifies the IPv4, IPv6, or L2 MAC multicast group address to
add. This setting is mandatory.
Added in version 247.
VLANId=
The VLAN ID for the new entry. Valid ranges are 0 (no VLAN) to
4094. Optional, defaults to 0.
Added in version 247.
The [LLDP] section manages the Link Layer Discovery Protocol
(LLDP) and accepts the following keys:
MUDURL=
When configured, the specified Manufacturer Usage Descriptions
(MUD) URL will be sent in LLDP packets. The syntax and
semantics are the same as for MUDURL= in the [DHCPv4] section
described above.
The MUD URLs received via LLDP packets are saved and can be
read using the sd_lldp_neighbor_get_mud_url() function.
Added in version 246.
The [CAN] section manages the Controller Area Network (CAN bus)
and accepts the following keys:
BitRate=
The bitrate of CAN device in bits per second. The usual SI
prefixes (K, M) with the base of 1000 can be used here. Takes
a number in the range 1...4294967295.
Added in version 239.
SamplePoint=
Optional sample point in percent with one decimal (e.g.
"75%", "87.5%") or permille (e.g. "875‰"). This will be
ignored when BitRate= is unspecified.
Added in version 239.
TimeQuantaNSec=, PropagationSegment=, PhaseBufferSegment1=,
PhaseBufferSegment2=, SyncJumpWidth=
Specifies the time quanta, propagation segment, phase buffer
segment 1 and 2, and the synchronization jump width, which
allow one to define the CAN bit-timing in a hardware
independent format as proposed by the Bosch CAN 2.0
Specification. TimeQuantaNSec= takes a timespan in
nanoseconds. PropagationSegment=, PhaseBufferSegment1=,
PhaseBufferSegment2=, and SyncJumpWidth= take number of time
quantum specified in TimeQuantaNSec= and must be an unsigned
integer in the range 0...4294967295. These settings except for
SyncJumpWidth= will be ignored when BitRate= is specified.
Added in version 250.
DataBitRate=, DataSamplePoint=
The bitrate and sample point for the data phase, if CAN-FD is
used. These settings are analogous to the BitRate= and
SamplePoint= keys.
Added in version 246.
DataTimeQuantaNSec=, DataPropagationSegment=,
DataPhaseBufferSegment1=, DataPhaseBufferSegment2=,
DataSyncJumpWidth=
Specifies the time quanta, propagation segment, phase buffer
segment 1 and 2, and the synchronization jump width for the
data phase, if CAN-FD is used. These settings are analogous to
the TimeQuantaNSec= or related settings.
Added in version 250.
FDMode=
Takes a boolean. When "yes", CAN-FD mode is enabled for the
interface. Note, that a bitrate and optional sample point
should also be set for the CAN-FD data phase using the
DataBitRate= and DataSamplePoint= keys, or DataTimeQuanta= and
related settings.
Added in version 246.
FDNonISO=
Takes a boolean. When "yes", non-ISO CAN-FD mode is enabled
for the interface. When unset, the kernel's default will be
used.
Added in version 246.
RestartSec=
Automatic restart delay time. If set to a non-zero value, a
restart of the CAN controller will be triggered automatically
in case of a bus-off condition after the specified delay time.
Subsecond delays can be specified using decimals (e.g.
"0.1s") or a "ms" or "us" postfix. Using "infinity" or "0"
will turn the automatic restart off. By default, automatic
restart is disabled.
Added in version 239.
Termination=
Takes a boolean or a termination resistor value in ohm in the
range 0...65535. When "yes", the termination resistor is set
to 120 ohm. When "no" or "0" is set, the termination resistor
is disabled. When unset, the kernel's default will be used.
Added in version 246.
TripleSampling=
Takes a boolean. When "yes", three samples (instead of one)
are used to determine the value of a received bit by majority
rule. When unset, the kernel's default will be used.
Added in version 242.
BusErrorReporting=
Takes a boolean. When "yes", reporting of CAN bus errors is
activated (those include single bit, frame format, and bit
stuffing errors, unable to send dominant bit, unable to send
recessive bit, bus overload, active error announcement, error
occurred on transmission). When unset, the kernel's default
will be used. Note: in case of a CAN bus with a single CAN
device, sending a CAN frame may result in a huge number of CAN
bus errors.
Added in version 248.
ListenOnly=
Takes a boolean. When "yes", listen-only mode is enabled. When
the interface is in listen-only mode, the interface neither
transmit CAN frames nor send ACK bit. Listen-only mode is
important to debug CAN networks without interfering with the
communication or acknowledge the CAN frame. When unset, the
kernel's default will be used.
Added in version 246.
Loopback=
Takes a boolean. When "yes", loopback mode is enabled. When
the loopback mode is enabled, the interface treats messages
transmitted by itself as received messages. The loopback mode
is important to debug CAN networks. When unset, the kernel's
default will be used.
Added in version 250.
OneShot=
Takes a boolean. When "yes", one-shot mode is enabled. When
unset, the kernel's default will be used.
Added in version 250.
PresumeAck=
Takes a boolean. When "yes", the interface will ignore missing
CAN ACKs. When unset, the kernel's default will be used.
Added in version 250.
ClassicDataLengthCode=
Takes a boolean. When "yes", the interface will handle the
4bit data length code (DLC). When unset, the kernel's default
will be used.
Added in version 250.
The [IPoIB] section manages the IP over Infiniband and accepts the
following keys:
Mode=
Takes one of the special values "datagram" or "connected".
Defaults to unset, and the kernel's default is used.
When "datagram", the Infiniband unreliable datagram (UD)
transport is used, and so the interface MTU is equal to the IB
L2 MTU minus the IPoIB encapsulation header (4 bytes). For
example, in a typical IB fabric with a 2K MTU, the IPoIB MTU
will be 2048 - 4 = 2044 bytes.
When "connected", the Infiniband reliable connected (RC)
transport is used. Connected mode takes advantage of the
connected nature of the IB transport and allows an MTU up to
the maximal IP packet size of 64K, which reduces the number of
IP packets needed for handling large UDP datagrams, TCP
segments, etc and increases the performance for large
messages.
Added in version 250.
IgnoreUserspaceMulticastGroup=
Takes an boolean value. When true, the kernel ignores
multicast groups handled by userspace. Defaults to unset, and
the kernel's default is used.
Added in version 250.
The [QDisc] section manages the traffic control queueing
discipline (qdisc).
Parent=
Specifies the parent Queueing Discipline (qdisc). Takes one of
"clsact" or "ingress". This is mandatory.
Added in version 244.
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
The [NetworkEmulator] section manages the queueing discipline
(qdisc) of the network emulator. It can be used to configure the
kernel packet scheduler and simulate packet delay and loss for UDP
or TCP applications, or limit the bandwidth usage of a particular
service to simulate internet connections.
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
DelaySec=
Specifies the fixed amount of delay to be added to all packets
going out of the interface. Defaults to unset.
Added in version 245.
DelayJitterSec=
Specifies the chosen delay to be added to the packets outgoing
to the network interface. Defaults to unset.
Added in version 245.
PacketLimit=
Specifies the maximum number of packets the qdisc may hold
queued at a time. An unsigned integer in the range
0...4294967294. Defaults to 1000.
Added in version 245.
LossRate=
Specifies an independent loss probability to be added to the
packets outgoing from the network interface. Takes a
percentage value, suffixed with "%". Defaults to unset.
Added in version 245.
DuplicateRate=
Specifies that the chosen percent of packets is duplicated
before queuing them. Takes a percentage value, suffixed with
"%". Defaults to unset.
Added in version 245.
The [TokenBucketFilter] section manages the queueing discipline
(qdisc) of token bucket filter (tbf).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
LatencySec=
Specifies the latency parameter, which specifies the maximum
amount of time a packet can sit in the Token Bucket Filter
(TBF). Defaults to unset.
Added in version 245.
LimitBytes=
Takes the number of bytes that can be queued waiting for
tokens to become available. When the size is suffixed with K,
M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
respectively, to the base of 1024. Defaults to unset.
Added in version 246.
BurstBytes=
Specifies the size of the bucket. This is the maximum amount
of bytes that tokens can be available for instantaneous
transfer. When the size is suffixed with K, M, or G, it is
parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to
the base of 1024. Defaults to unset.
Added in version 246.
Rate=
Specifies the device specific bandwidth. When suffixed with K,
M, or G, the specified bandwidth is parsed as Kilobits,
Megabits, or Gigabits, respectively, to the base of 1000.
Defaults to unset.
Added in version 245.
MPUBytes=
The Minimum Packet Unit (MPU) determines the minimal token
usage (specified in bytes) for a packet. When suffixed with K,
M, or G, the specified size is parsed as Kilobytes, Megabytes,
or Gigabytes, respectively, to the base of 1024. Defaults to
zero.
Added in version 245.
PeakRate=
Takes the maximum depletion rate of the bucket. When suffixed
with K, M, or G, the specified size is parsed as Kilobits,
Megabits, or Gigabits, respectively, to the base of 1000.
Defaults to unset.
Added in version 245.
MTUBytes=
Specifies the size of the peakrate bucket. When suffixed with
K, M, or G, the specified size is parsed as Kilobytes,
Megabytes, or Gigabytes, respectively, to the base of 1024.
Defaults to unset.
Added in version 245.
The [PIE] section manages the queueing discipline (qdisc) of
Proportional Integral controller-Enhanced (PIE).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the queue size in number of
packets. When this limit is reached, incoming packets are
dropped. An unsigned integer in the range 1...4294967294.
Defaults to unset and kernel's default is used.
Added in version 246.
The "[FlowQueuePIE]" section manages the queueing discipline
(qdisc) of Flow Queue Proportional Integral controller-Enhanced
(fq_pie).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the queue size in number of
packets. When this limit is reached, incoming packets are
dropped. An unsigned integer ranges 1 to 4294967294. Defaults
to unset and kernel's default is used.
Added in version 247.
The [StochasticFairBlue] section manages the queueing discipline
(qdisc) of stochastic fair blue (sfb).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the queue size in number of
packets. When this limit is reached, incoming packets are
dropped. An unsigned integer in the range 0...4294967294.
Defaults to unset and kernel's default is used.
Added in version 246.
The [StochasticFairnessQueueing] section manages the queueing
discipline (qdisc) of stochastic fairness queueing (sfq).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PerturbPeriodSec=
Specifies the interval in seconds for queue algorithm
perturbation. Defaults to unset.
Added in version 245.
The [BFIFO] section manages the queueing discipline (qdisc) of
Byte limited Packet First In First Out (bfifo).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
LimitBytes=
Specifies the hard limit in bytes on the FIFO buffer size. The
size limit prevents overflow in case the kernel is unable to
dequeue packets as quickly as it receives them. When this
limit is reached, incoming packets are dropped. When suffixed
with K, M, or G, the specified size is parsed as Kilobytes,
Megabytes, or Gigabytes, respectively, to the base of 1024.
Defaults to unset and kernel default is used.
Added in version 246.
The [PFIFO] section manages the queueing discipline (qdisc) of
Packet First In First Out (pfifo).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the number of packets in the FIFO
queue. The size limit prevents overflow in case the kernel is
unable to dequeue packets as quickly as it receives them. When
this limit is reached, incoming packets are dropped. An
unsigned integer in the range 0...4294967294. Defaults to
unset and kernel's default is used.
Added in version 246.
The [PFIFOHeadDrop] section manages the queueing discipline
(qdisc) of Packet First In First Out Head Drop (pfifo_head_drop).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
As in [PFIFO] section.
Added in version 246.
The [PFIFOFast] section manages the queueing discipline (qdisc) of
Packet First In First Out Fast (pfifo_fast).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
The [CAKE] section manages the queueing discipline (qdisc) of
Common Applications Kept Enhanced (CAKE).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
Bandwidth=
Specifies the shaper bandwidth. When suffixed with K, M, or G,
the specified size is parsed as Kilobits, Megabits, or
Gigabits, respectively, to the base of 1000. Defaults to unset
and kernel's default is used.
Added in version 246.
AutoRateIngress=
Takes a boolean value. Enables automatic capacity estimation
based on traffic arriving at this qdisc. This is most likely
to be useful with cellular links, which tend to change quality
randomly. If this setting is enabled, the Bandwidth= setting
is used as an initial estimate. Defaults to unset, and the
kernel's default is used.
Added in version 250.
OverheadBytes=
Specifies that bytes to be addeded to the size of each packet.
Bytes may be negative. Takes an integer in the range
-64...256. Defaults to unset and kernel's default is used.
Added in version 246.
MPUBytes=
Rounds each packet (including overhead) up to the specified
bytes. Takes an integer in the range 1...256. Defaults to
unset and kernel's default is used.
Added in version 250.
CompensationMode=
Takes one of "none", "atm", or "ptm". Specifies the
compensation mode for overhead calculation. When "none", no
compensation is taken into account. When "atm", enables the
compensation for ATM cell framing, which is normally found on
ADSL links. When "ptm", enables the compensation for PTM
encoding, which is normally found on VDSL2 links and uses a
64b/65b encoding scheme. Defaults to unset and the kernel's
default is used.
Added in version 250.
UseRawPacketSize=
Takes a boolean value. When true, the packet size reported by
the Linux kernel will be used, instead of the underlying IP
packet size. Defaults to unset, and the kernel's default is
used.
Added in version 250.
FlowIsolationMode=
CAKE places packets from different flows into different
queues, then packets from each queue are delivered fairly.
This specifies whether the fairness is based on source
address, destination address, individual flows, or any
combination of those. The available values are:
none
The flow isolation is disabled, and all traffic passes
through a single queue.
Added in version 250.
src-host
Flows are defined only by source address. Equivalent to
the "srchost" option for tc qdisc command. See also
tc-cake(8).
Added in version 250.
dst-host
Flows are defined only by destination address. Equivalent
to the "dsthost" option for tc qdisc command. See also
tc-cake(8).
Added in version 250.
hosts
Flows are defined by source-destination host pairs.
Equivalent to the same option for tc qdisc command. See
also tc-cake(8).
Added in version 250.
flows
Flows are defined by the entire 5-tuple of source address,
destination address, transport protocol, source port and
destination port. Equivalent to the same option for tc
qdisc command. See also tc-cake(8).
Added in version 250.
dual-src-host
Flows are defined by the 5-tuple (see "flows" in the
above), and fairness is applied first over source
addresses, then over individual flows. Equivalent to the
"dual-srchost" option for tc qdisc command. See also
tc-cake(8).
Added in version 250.
dual-dst-host
Flows are defined by the 5-tuple (see "flows" in the
above), and fairness is applied first over destination
addresses, then over individual flows. Equivalent to the
"dual-dsthost" option for tc qdisc command. See also
tc-cake(8).
Added in version 250.
triple
Flows are defined by the 5-tuple (see "flows"), and
fairness is applied over source and destination addresses,
and also over individual flows. Equivalent to the
"triple-isolate" option for tc qdisc command. See also
tc-cake(8).
Added in version 250.
Defaults to unset and the kernel's default is used.
Added in version 250.
NAT=
Takes a boolean value. When true, CAKE performs a NAT lookup
before applying flow-isolation rules, to determine the true
addresses and port numbers of the packet, to improve fairness
between hosts inside the NAT. This has no practical effect
when FlowIsolationMode= is "none" or "flows", or if NAT is
performed on a different host. Defaults to unset, and the
kernel's default is used.
Added in version 250.
PriorityQueueingPreset=
CAKE divides traffic into "tins", and each tin has its own
independent set of flow-isolation queues, bandwidth threshold,
and priority. This specifies the preset of tin profiles. The
available values are:
besteffort
Disables priority queueing by placing all traffic in one
tin.
Added in version 250.
precedence
Enables priority queueing based on the legacy
interpretation of TOS "Precedence" field. Use of this
preset on the modern Internet is firmly discouraged.
Added in version 250.
diffserv8
Enables priority queueing based on the Differentiated
Service ("DiffServ") field with eight tins: Background
Traffic, High Throughput, Best Effort, Video Streaming,
Low Latency Transactions, Interactive Shell, Minimum
Latency, and Network Control.
Added in version 250.
diffserv4
Enables priority queueing based on the Differentiated
Service ("DiffServ") field with four tins: Background
Traffic, Best Effort, Streaming Media, and Latency
Sensitive.
Added in version 250.
diffserv3
Enables priority queueing based on the Differentiated
Service ("DiffServ") field with three tins: Background
Traffic, Best Effort, and Latency Sensitive.
Added in version 250.
Defaults to unset, and the kernel's default is used.
Added in version 250.
FirewallMark=
Takes an integer in the range 1...4294967295. When specified,
firewall-mark-based overriding of CAKE's tin selection is
enabled. Defaults to unset, and the kernel's default is used.
Added in version 250.
Wash=
Takes a boolean value. When true, CAKE clears the DSCP fields,
except for ECN bits, of any packet passing through CAKE.
Defaults to unset, and the kernel's default is used.
Added in version 250.
SplitGSO=
Takes a boolean value. When true, CAKE will split General
Segmentation Offload (GSO) super-packets into their
on-the-wire components and dequeue them individually. Defaults
to unset, and the kernel's default is used.
Added in version 250.
RTTSec=
Specifies the RTT for the filter. Takes a timespan. Typical
values are e.g. 100us for extremely high-performance 10GigE+
networks like datacentre, 1ms for non-WiFi LAN connections,
100ms for typical internet connections. Defaults to unset, and
the kernel's default will be used.
Added in version 253.
AckFilter=
Takes a boolean value, or special value "aggressive". If
enabled, ACKs in each flow are queued and redundant ACKs to
the upstream are dropped. If yes, the filter will always keep
at least two redundant ACKs in the queue, while in
"aggressive" mode, it will filter down to a single ACK. This
may improve download throughput on links with very
asymmetrical rate limits. Defaults to unset, and the kernel's
default will be used.
Added in version 253.
The [ControlledDelay] section manages the queueing discipline
(qdisc) of controlled delay (CoDel).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the queue size in number of
packets. When this limit is reached, incoming packets are
dropped. An unsigned integer in the range 0...4294967294.
Defaults to unset and kernel's default is used.
Added in version 245.
TargetSec=
Takes a timespan. Specifies the acceptable minimum
standing/persistent queue delay. Defaults to unset and
kernel's default is used.
Added in version 245.
IntervalSec=
Takes a timespan. This is used to ensure that the measured
minimum delay does not become too stale. Defaults to unset and
kernel's default is used.
Added in version 245.
ECN=
Takes a boolean. This can be used to mark packets instead of
dropping them. Defaults to unset and kernel's default is used.
Added in version 245.
CEThresholdSec=
Takes a timespan. This sets a threshold above which all
packets are marked with ECN Congestion Experienced (CE).
Defaults to unset and kernel's default is used.
Added in version 245.
The [DeficitRoundRobinScheduler] section manages the queueing
discipline (qdisc) of Deficit Round Robin Scheduler (DRR).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
The [DeficitRoundRobinSchedulerClass] section manages the traffic
control class of Deficit Round Robin Scheduler (DRR).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", or a qdisc identifier. The qdisc identifier is
specified as the major and minor numbers in hexadecimal in the
range 0x1–0xffff separated with a colon ("major:minor").
Defaults to "root".
ClassId=
Configures the unique identifier of the class. It is specified
as the major and minor numbers in hexadecimal in the range
0x1–0xffff separated with a colon ("major:minor"). Defaults to
unset.
QuantumBytes=
Specifies the amount of bytes a flow is allowed to dequeue
before the scheduler moves to the next class. When suffixed
with K, M, or G, the specified size is parsed as Kilobytes,
Megabytes, or Gigabytes, respectively, to the base of 1024.
Defaults to the MTU of the interface.
Added in version 246.
The [EnhancedTransmissionSelection] section manages the queueing
discipline (qdisc) of Enhanced Transmission Selection (ETS).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
Bands=
Specifies the number of bands. An unsigned integer in the
range 1...16. This value has to be at least large enough to
cover the strict bands specified through the StrictBands= and
bandwidth-sharing bands specified in QuantumBytes=.
Added in version 246.
StrictBands=
Specifies the number of bands that should be created in strict
mode. An unsigned integer in the range 1...16.
Added in version 246.
QuantumBytes=
Specifies the white-space separated list of quantum used in
band-sharing bands. When suffixed with K, M, or G, the
specified size is parsed as Kilobytes, Megabytes, or
Gigabytes, respectively, to the base of 1024. This setting can
be specified multiple times. If an empty string is assigned,
then the all previous assignments are cleared.
Added in version 246.
PriorityMap=
The priority map maps the priority of a packet to a band. The
argument is a whitespace separated list of numbers. The first
number indicates which band the packets with priority 0 should
be put to, the second is for priority 1, and so on. There can
be up to 16 numbers in the list. If there are fewer, the
default band that traffic with one of the unmentioned
priorities goes to is the last one. Each band number must be
in the range 0...255. This setting can be specified multiple
times. If an empty string is assigned, then the all previous
assignments are cleared.
Added in version 246.
The [GenericRandomEarlyDetection] section manages the queueing
discipline (qdisc) of Generic Random Early Detection (GRED).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
VirtualQueues=
Specifies the number of virtual queues. Takes an integer in
the range 1...16. Defaults to unset and kernel's default is
used.
Added in version 246.
DefaultVirtualQueue=
Specifies the number of default virtual queue. This must be
less than VirtualQueue=. Defaults to unset and kernel's
default is used.
Added in version 246.
GenericRIO=
Takes a boolean. It turns on the RIO-like buffering scheme.
Defaults to unset and kernel's default is used.
Added in version 246.
The [FairQueueingControlledDelay] section manages the queueing
discipline (qdisc) of fair queuing controlled delay (FQ-CoDel).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the real queue size. When this
limit is reached, incoming packets are dropped. Defaults to
unset and kernel's default is used.
Added in version 245.
MemoryLimitBytes=
Specifies the limit on the total number of bytes that can be
queued in this FQ-CoDel instance. When suffixed with K, M, or
G, the specified size is parsed as Kilobytes, Megabytes, or
Gigabytes, respectively, to the base of 1024. Defaults to
unset and kernel's default is used.
Added in version 246.
Flows=
Specifies the number of flows into which the incoming packets
are classified. Defaults to unset and kernel's default is
used.
Added in version 245.
TargetSec=
Takes a timespan. Specifies the acceptable minimum
standing/persistent queue delay. Defaults to unset and
kernel's default is used.
Added in version 245.
IntervalSec=
Takes a timespan. This is used to ensure that the measured
minimum delay does not become too stale. Defaults to unset and
kernel's default is used.
Added in version 245.
QuantumBytes=
Specifies the number of bytes used as the "deficit" in the
fair queuing algorithm timespan. When suffixed with K, M, or
G, the specified size is parsed as Kilobytes, Megabytes, or
Gigabytes, respectively, to the base of 1024. Defaults to
unset and kernel's default is used.
Added in version 246.
ECN=
Takes a boolean. This can be used to mark packets instead of
dropping them. Defaults to unset and kernel's default is used.
Added in version 245.
CEThresholdSec=
Takes a timespan. This sets a threshold above which all
packets are marked with ECN Congestion Experienced (CE).
Defaults to unset and kernel's default is used.
Added in version 245.
The [FairQueueing] section manages the queueing discipline (qdisc)
of fair queue traffic policing (FQ).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the real queue size. When this
limit is reached, incoming packets are dropped. Defaults to
unset and kernel's default is used.
Added in version 245.
FlowLimit=
Specifies the hard limit on the maximum number of packets
queued per flow. Defaults to unset and kernel's default is
used.
Added in version 245.
QuantumBytes=
Specifies the credit per dequeue RR round, i.e. the amount of
bytes a flow is allowed to dequeue at once. When suffixed with
K, M, or G, the specified size is parsed as Kilobytes,
Megabytes, or Gigabytes, respectively, to the base of 1024.
Defaults to unset and kernel's default is used.
Added in version 246.
InitialQuantumBytes=
Specifies the initial sending rate credit, i.e. the amount of
bytes a new flow is allowed to dequeue initially. When
suffixed with K, M, or G, the specified size is parsed as
Kilobytes, Megabytes, or Gigabytes, respectively, to the base
of 1024. Defaults to unset and kernel's default is used.
Added in version 245.
MaximumRate=
Specifies the maximum sending rate of a flow. When suffixed
with K, M, or G, the specified size is parsed as Kilobits,
Megabits, or Gigabits, respectively, to the base of 1000.
Defaults to unset and kernel's default is used.
Added in version 245.
Buckets=
Specifies the size of the hash table used for flow lookups.
Defaults to unset and kernel's default is used.
Added in version 245.
OrphanMask=
Takes an unsigned integer. For packets not owned by a socket,
fq is able to mask a part of hash and reduce number of buckets
associated with the traffic. Defaults to unset and kernel's
default is used.
Added in version 245.
Pacing=
Takes a boolean, and enables or disables flow pacing. Defaults
to unset and kernel's default is used.
Added in version 245.
CEThresholdSec=
Takes a timespan. This sets a threshold above which all
packets are marked with ECN Congestion Experienced (CE).
Defaults to unset and kernel's default is used.
Added in version 245.
The [TrivialLinkEqualizer] section manages the queueing discipline
(qdisc) of trivial link equalizer (teql).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
Id=
Specifies the interface ID "N" of teql. Defaults to "0". Note
that when teql is used, currently, the module sch_teql with
max_equalizers=N+1 option must be loaded before
systemd-networkd is started.
Added in version 245.
The [HierarchyTokenBucket] section manages the queueing discipline
(qdisc) of hierarchy token bucket (htb).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
DefaultClass=
Takes the minor id in hexadecimal of the default class.
Unclassified traffic gets sent to the class. Defaults to
unset.
Added in version 246.
RateToQuantum=
Takes an unsigned integer. The DRR quantums are calculated by
dividing the value configured in Rate= by RateToQuantum=.
Added in version 246.
The [HierarchyTokenBucketClass] section manages the traffic
control class of hierarchy token bucket (htb).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", or a qdisc identifier. The qdisc identifier is
specified as the major and minor numbers in hexadecimal in the
range 0x1–0xffff separated with a colon ("major:minor").
Defaults to "root".
ClassId=
Configures the unique identifier of the class. It is specified
as the major and minor numbers in hexadecimal in the range
0x1–0xffff separated with a colon ("major:minor"). Defaults to
unset.
Priority=
Specifies the priority of the class. In the round-robin
process, classes with the lowest priority field are tried for
packets first.
Added in version 246.
QuantumBytes=
Specifies how many bytes to serve from leaf at once. When
suffixed with K, M, or G, the specified size is parsed as
Kilobytes, Megabytes, or Gigabytes, respectively, to the base
of 1024.
Added in version 246.
MTUBytes=
Specifies the maximum packet size we create. When suffixed
with K, M, or G, the specified size is parsed as Kilobytes,
Megabytes, or Gigabytes, respectively, to the base of 1024.
Added in version 246.
OverheadBytes=
Takes an unsigned integer which specifies per-packet size
overhead used in rate computations. When suffixed with K, M,
or G, the specified size is parsed as Kilobytes, Megabytes, or
Gigabytes, respectively, to the base of 1024.
Added in version 246.
Rate=
Specifies the maximum rate this class and all its children are
guaranteed. When suffixed with K, M, or G, the specified size
is parsed as Kilobits, Megabits, or Gigabits, respectively, to
the base of 1000. This setting is mandatory.
Added in version 246.
CeilRate=
Specifies the maximum rate at which a class can send, if its
parent has bandwidth to spare. When suffixed with K, M, or G,
the specified size is parsed as Kilobits, Megabits, or
Gigabits, respectively, to the base of 1000. When unset, the
value specified with Rate= is used.
Added in version 246.
BufferBytes=
Specifies the maximum bytes burst which can be accumulated
during idle period. When suffixed with K, M, or G, the
specified size is parsed as Kilobytes, Megabytes, or
Gigabytes, respectively, to the base of 1024.
Added in version 246.
CeilBufferBytes=
Specifies the maximum bytes burst for ceil which can be
accumulated during idle period. When suffixed with K, M, or G,
the specified size is parsed as Kilobytes, Megabytes, or
Gigabytes, respectively, to the base of 1024.
Added in version 246.
The [ClassfulMultiQueueing] section manages the queueing
discipline (qdisc) of Classful Multi Queueing (mq).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
The [BandMultiQueueing] section manages the queueing discipline
(qdisc) of Band Multi Queueing (multiq).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
The [HeavyHitterFilter] section manages the queueing discipline
(qdisc) of Heavy Hitter Filter (hhf).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the queue size in number of
packets. When this limit is reached, incoming packets are
dropped. An unsigned integer in the range 0...4294967294.
Defaults to unset and kernel's default is used.
Added in version 246.
The [QuickFairQueueing] section manages the queueing discipline
(qdisc) of Quick Fair Queueing (QFQ).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", "clsact", "ingress" or a class identifier. The
class identifier is specified as the major and minor numbers
in hexadecimal in the range 0x1–0xffff separated with a colon
("major:minor"). Defaults to "root".
Handle=
Configures the major number of unique identifier of the qdisc,
known as the handle. Takes a hexadecimal number in the range
0x1–0xffff. Defaults to unset.
The [QuickFairQueueingClass] section manages the traffic control
class of Quick Fair Queueing (qfq).
Parent=
Configures the parent Queueing Discipline (qdisc). Takes one
of "root", or a qdisc identifier. The qdisc identifier is
specified as the major and minor numbers in hexadecimal in the
range 0x1–0xffff separated with a colon ("major:minor").
Defaults to "root".
ClassId=
Configures the unique identifier of the class. It is specified
as the major and minor numbers in hexadecimal in the range
0x1–0xffff separated with a colon ("major:minor"). Defaults to
unset.
Weight=
Specifies the weight of the class. Takes an integer in the
range 1...1023. Defaults to unset in which case the kernel
default is used.
Added in version 246.
MaxPacketBytes=
Specifies the maximum packet size in bytes for the class. When
suffixed with K, M, or G, the specified size is parsed as
Kilobytes, Megabytes, or Gigabytes, respectively, to the base
of 1024. When unset, the kernel default is used.
Added in version 246.
The [BridgeVLAN] section manages the VLAN ID configurations of a
bridge master or port, and accepts the following keys. To make the
settings in this section take an effect, VLANFiltering= option has
to be enabled on the bridge master, see the [Bridge] section in
systemd.netdev(5). If at least one valid settings specified in
this section in a .network file for an interface, all assigned
VLAN IDs on the interface that are not configured in the .network
file will be removed. If VLAN IDs on an interface need to be
managed by other tools, then the settings in this section cannot
be used in the matching .network file.
VLAN=
The VLAN ID allowed on the port. This can be either a single
ID or a range M-N. Takes an integer in the range 1...4094.
This setting can be specified multiple times. If an empty
string is assigned, then the all previous assignments are
cleared.
Added in version 231.
EgressUntagged=
The VLAN ID specified here will be used to untag frames on
egress. Configuring EgressUntagged= implicates the use of
VLAN= above and will enable the VLAN ID for ingress as well.
This can be either a single ID or a range M-N. This setting
can be specified multiple times. If an empty string is
assigned, then the all previous assignments are cleared.
Added in version 231.
PVID=
The port VLAN ID specified here is assigned to all untagged
frames at ingress. Takes an VLAN ID or negative boolean value
(e.g. "no"). When false, the currently assigned port VLAN ID
will be dropped. Configuring PVID= implicates the use of VLAN=
setting in the above and will enable the VLAN ID for ingress
as well. Defaults to unset, and will keep the assigned port
VLAN ID if exists.
Added in version 231.
Example 1. Static network configuration
# /etc/systemd/network/50-static.network
[Match]
Name=enp2s0
[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
This brings interface "enp2s0" up with a static address. The
specified gateway will be used for a default route.
Example 2. DHCP on ethernet links
# /etc/systemd/network/80-dhcp.network
[Match]
Name=en*
[Network]
DHCP=yes
This will enable DHCPv4 and DHCPv6 on all interfaces with names
starting with "en" (i.e. ethernet interfaces).
Example 3. IPv6 Prefix Delegation (DHCPv6 PD)
# /etc/systemd/network/55-dhcpv6-pd-upstream.network
[Match]
Name=enp1s0
[Network]
DHCP=ipv6
# The lines below are optional, to also assign an address in the delegated prefix
# to the upstream interface. Uncomment the lines below if necessary.
#[Network]
#DHCPPrefixDelegation=yes
#[DHCPPrefixDelegation]
#UplinkInterface=:self
#SubnetId=0
#Announce=no
# If the upstream network does not provides any Router Advertisement (RA) messages,
# then uncomment the lines below to make the DHCPv6 client forcibly started in the
# managed mode.
#[Network]
#IPv6AcceptRA=no
#[DHCPv6]
#WithoutRA=solicit
# If the upstream network provides Router Advertisement (RA) messages with the
# Managed bit unset, then uncomment the lines below to make the DHCPv6 client
# forcibly started in the managed mode when an RA is received.
#[DHCPv6]
#UseAddress=no
#[IPv6AcceptRA]
#DHCPv6Client=always
# /etc/systemd/network/55-dhcpv6-pd-downstream.network
[Match]
Name=enp2s0
[Network]
DHCPPrefixDelegation=yes
IPv6SendRA=yes
# It is expected that the host is acting as a router. So, usually it is not
# necessary to receive Router Advertisement from other hosts in the downstream network.
IPv6AcceptRA=no
[DHCPPrefixDelegation]
UplinkInterface=enp1s0
SubnetId=1
Announce=yes
This will enable DHCPv6-PD on the interface enp1s0 as an upstream
interface where the DHCPv6 client is running and enp2s0 as a
downstream interface where the prefix is delegated to. The
delegated prefixes are distributed by IPv6 Router Advertisement on
the downstream network.
Example 4. IPv6 Prefix Delegation (DHCPv4 6RD)
# /etc/systemd/network/55-dhcpv4-6rd-upstream.network
[Match]
Name=enp1s0
[Network]
DHCP=ipv4
# When DHCPv4-6RD is used, the upstream network does not support IPv6.
# Hence, it is not necessary to wait for Router Advertisement, which is enabled by default.
IPv6AcceptRA=no
[DHCPv4]
Use6RD=yes
# /etc/systemd/network/55-dhcpv4-6rd-downstream.network
[Match]
Name=enp2s0
[Network]
DHCPPrefixDelegation=yes
IPv6SendRA=yes
# It is expected that the host is acting as a router. So, usually it is not
# necessary to receive Router Advertisement from other hosts in the downstream network.
IPv6AcceptRA=no
[DHCPPrefixDelegation]
UplinkInterface=enp1s0
SubnetId=1
Announce=yes
This will enable DHCPv4-6RD on the interface enp1s0 as an upstream
interface where the DHCPv4 client is running and enp2s0 as a
downstream interface where the prefix is delegated to. The
delegated prefixes are distributed by IPv6 Router Advertisement on
the downstream network.
Example 5. A bridge with two enslaved links
# /etc/systemd/network/25-bridge-static.netdev
[NetDev]
Name=bridge0
Kind=bridge
# /etc/systemd/network/25-bridge-static.network
[Match]
Name=bridge0
[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
DNS=192.168.0.1
# /etc/systemd/network/25-bridge-slave-interface-1.network
[Match]
Name=enp2s0
[Network]
Bridge=bridge0
# /etc/systemd/network/25-bridge-slave-interface-2.network
[Match]
Name=wlp3s0
[Network]
Bridge=bridge0
This creates a bridge and attaches devices "enp2s0" and "wlp3s0"
to it. The bridge will have the specified static address and
network assigned, and a default route via the specified gateway
will be added. The specified DNS server will be added to the
global list of DNS resolvers.
Example 6. Bridge port with VLAN forwarding
# /etc/systemd/network/25-bridge-slave-interface-1.network
[Match]
Name=enp2s0
[Network]
Bridge=bridge0
[BridgeVLAN]
VLAN=1-32
PVID=42
EgressUntagged=42
[BridgeVLAN]
VLAN=100-299
[BridgeVLAN]
EgressUntagged=300-400
This overrides the configuration specified in the previous example
for the interface "enp2s0", and enables VLAN on that bridge port.
VLAN IDs 1-32, 42, 100-400 will be allowed. Packets tagged with
VLAN IDs 42, 300-400 will be untagged when they leave on this
interface. Untagged packets which arrive on this interface will be
assigned VLAN ID 42.
Example 7. Various tunnels
/etc/systemd/network/25-tunnels.network
[Match]
Name=ens1
[Network]
Tunnel=ipip-tun
Tunnel=sit-tun
Tunnel=gre-tun
Tunnel=vti-tun
/etc/systemd/network/25-tunnel-ipip.netdev
[NetDev]
Name=ipip-tun
Kind=ipip
/etc/systemd/network/25-tunnel-sit.netdev
[NetDev]
Name=sit-tun
Kind=sit
/etc/systemd/network/25-tunnel-gre.netdev
[NetDev]
Name=gre-tun
Kind=gre
/etc/systemd/network/25-tunnel-vti.netdev
[NetDev]
Name=vti-tun
Kind=vti
This will bring interface "ens1" up and create an IPIP tunnel, a
SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
Example 8. A bond device
# /etc/systemd/network/30-bond1.network
[Match]
Name=bond1
[Network]
DHCP=ipv6
# /etc/systemd/network/30-bond1.netdev
[NetDev]
Name=bond1
Kind=bond
# /etc/systemd/network/30-bond1-dev1.network
[Match]
MACAddress=52:54:00:e9:64:41
[Network]
Bond=bond1
# /etc/systemd/network/30-bond1-dev2.network
[Match]
MACAddress=52:54:00:e9:64:42
[Network]
Bond=bond1
This will create a bond device "bond1" and enslave the two devices
with MAC addresses 52:54:00:e9:64:41 and 52:54:00:e9:64:42 to it.
IPv6 DHCP will be used to acquire an address.
Example 9. Virtual Routing and Forwarding (VRF)
Add the "bond1" interface to the VRF master interface "vrf1". This
will redirect routes generated on this interface to be within the
routing table defined during VRF creation. For kernels before 4.8
traffic will not be redirected towards the VRFs routing table
unless specific ip-rules are added.
# /etc/systemd/network/25-vrf.network
[Match]
Name=bond1
[Network]
VRF=vrf1
Example 10. MacVTap
This brings up a network interface "macvtap-test" and attaches it
to "enp0s25".
# /usr/lib/systemd/network/25-macvtap.network
[Match]
Name=enp0s25
[Network]
MACVTAP=macvtap-test
Example 11. A Xfrm interface with physical underlying device.
# /etc/systemd/network/27-xfrm.netdev
[NetDev]
Name=xfrm0
Kind=xfrm
[Xfrm]
InterfaceId=7
# /etc/systemd/network/27-eth0.network
[Match]
Name=eth0
[Network]
Xfrm=xfrm0
This creates a "xfrm0" interface and binds it to the "eth0"
device. This allows hardware based ipsec offloading to the "eth0"
nic. If offloading is not needed, xfrm interfaces can be assigned
to the "lo" device.
systemd(1), systemd-networkd.service(8), systemd.link(5),
systemd.netdev(5), systemd-network-generator.service(8),
systemd-resolved.service(8)
1. 💣💥🧨💥💥💣 Please note that those configuration files must
be available at all times. If /usr/local/ is a separate
partition, it may not be available during early boot, and must
not be used for configuration.
2. System and Service Credentials
https://systemd.io/CREDENTIALS
3. Link-Local Multicast Name Resolution
https://tools.ietf.org/html/rfc4795
4. Multicast DNS
https://tools.ietf.org/html/rfc6762
5. DNS-over-TLS
https://tools.ietf.org/html/rfc7858
6. DNSSEC
https://tools.ietf.org/html/rfc4033
7. IEEE 802.1AB-2016
https://standards.ieee.org/findstds/standard/802.1AB-2016.html
8. RFC 5227
https://tools.ietf.org/html/rfc5227
9. IP Sysctl
https://docs.kernel.org/networking/ip-sysctl.html
10. RFC 4941
https://tools.ietf.org/html/rfc4941
11. RFC 3704
https://tools.ietf.org/html/rfc1027
12. RFC 3069
https://tools.ietf.org/html/rfc3069
13. RFC 6275
https://tools.ietf.org/html/rfc6275
14. RFC 4862
https://tools.ietf.org/html/rfc4862
15. RFC 3041
https://tools.ietf.org/html/rfc3041
16. NetLabel
https://docs.kernel.org/netlabel/index.html
17. Linux Security Modules (LSMs)
https://en.wikipedia.org/wiki/Linux_Security_Modules
18. NetLabel Fallback Peer Labeling
https://github.com/SELinuxProject/selinux-notebook/blob/main/src/network_support.md
19. NFT
https://netfilter.org/projects/nftables/index.html
20. RFC 3484
https://tools.ietf.org/html/rfc3484
21. Type of Service
https://en.wikipedia.org/wiki/Type_of_service
22. Differentiated services
https://en.wikipedia.org/wiki/Differentiated_services
23. Virtual Routing and Forwarding (VRF)
https://docs.kernel.org/networking/vrf.html
24. RFC 4191
https://tools.ietf.org/html/rfc4191
25. RFC 8520
https://tools.ietf.org/html/rfc8520
26. RFC 4039
https://tools.ietf.org/html/rfc4039
27. RFC 7844
https://tools.ietf.org/html/rfc7844
28. C-style escapes
https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences
29. RFC 9463
https://datatracker.ietf.org/doc/html/rfc9463
30. RFC 3442
https://datatracker.ietf.org/doc/html/rfc3442
31. RFC 5969
https://tools.ietf.org/html/rfc5969
32. RFC 7084
https://datatracker.ietf.org/doc/html/rfc7084
33. RFC 8925
https://tools.ietf.org/html/rfc8925
34. RFC 3315
https://tools.ietf.org/html/rfc3315#section-17.2.1
35. RFC 8415
https://www.rfc-editor.org/rfc/rfc8415.html#section-6.3
36. RFC 4291
https://tools.ietf.org/html/rfc4291#section-2.5.4
37. RFC 7217
https://tools.ietf.org/html/rfc7217
38. RFC 8781
https://tools.ietf.org/html/rfc8781
39. RFC 2131
https://www.rfc-editor.org/rfc/rfc2131.html
40. RFC 2132
https://www.rfc-editor.org/rfc/rfc2132.html
41. RFC 1542
https://tools.ietf.org/html/rfc1542
42. RFC 4039
https://datatracker.ietf.org/doc/html/rfc4039
43. RFC 4861
https://tools.ietf.org/html/rfc4861
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-02-02. (At that
time, the date of the most recent commit that was found in the
repository was 2025-02-02.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~devel SYSTEMD.NETWORK(5)
Pages that refer to this page: networkctl(1), resolvectl(1), dnssec-trust-anchors.d(5), networkd.conf(5), systemd.link(5), systemd.netdev(5), systemd.directives(7), systemd.index(7), systemd.syntax(7), systemd.system-credentials(7), systemd-networkd.service(8), systemd-network-generator.service(8), systemd-resolved.service(8), systemd-timesyncd.service(8)
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