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, 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 (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.
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".
hyphen-delimited hexadecimal
Each field must be one byte. E.g. "12-34-56-78-90-ab" or
"AA-BB-CC-DD-EE-FF".
dot-delimited hexadecimal
Each field must be two bytes. E.g. "1234.5678.90ab" or
"AABB.CCDD.EEFF".
IPv4 address format
E.g. "127.0.0.1" or "192.168.0.1".
IPv6 address format
E.g. "2001:0db8:85a3::8a2e:0370:7334" or "::1".
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.
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.
Path=
A whitespace-separated list of shell-style globs matching the
persistent path, as exposed by the udev property ID_PATH.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Credential=
Checks whether the specified credential was passed to the
systemd-networkd.service service. See System and Service
Credentials[1] for details. When prefixed with an exclamation
mark ("!"), the result is negated. If an empty string is
assigned, the previously assigned value is cleared.
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.
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.
The [Link] section accepts the following keys:
MACAddress=
The hardware address to set for the device.
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.
ARP=
Takes a boolean. If set to true, the ARP (low-level Address
Resolution Protocol) for this interface is 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.
Multicast=
Takes a boolean. If set to true, the multicast flag on the
device is enabled. Defaults to unset.
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.
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.
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.
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.
RequiredForOnline=
Takes a boolean or a minimum operational state and an
optional maximum operational state. 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, "yes" is implied, and this
controls the minimum and maximum operational state required
for the network interface to be considered online.
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".
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 "any". Note that this option
has no effect if "RequiredForOnline=no", or if
"RequiredForOnline=" specifies a minimum operational state
below "degraded".
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.
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.
VLANId=
Specifies VLAN ID of the virtual function. Takes an integer
in the range 1...4095.
QualityOfService=
Specifies quality of service of the virtual function. Takes
an integer in the range 1...4294967294.
VLANProtocol=
Specifies VLAN protocol of the virtual function. Takes
"802.1Q" or "802.1ad".
MACSpoofCheck=
Takes a boolean. Controls the MAC spoof checking. When unset,
the kernel's default will be used.
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.
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.
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.
MACAddress=
Specifies the MAC address for the virtual function.
The [Network] section accepts the following keys:
Description=
A description of the device. This is only used for
presentation purposes.
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.
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.
LinkLocalAddressing=
Enables link-local address autoconfiguration. Accepts yes,
no, 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.
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.
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.
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.
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.
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
LLMNR=
Takes a boolean or "resolve". When true, enables Link-Local
Multicast Name Resolution[2] 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).
MulticastDNS=
Takes a boolean or "resolve". When true, enables Multicast
DNS[3] 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).
DNSOverTLS=
Takes a boolean or "opportunistic". When true, enables
DNS-over-TLS[4] 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).
DNSSEC=
Takes a boolean or "allow-downgrade". When true, enables
DNSSEC[5] 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).
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).
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.
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[6]. 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.
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".
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.
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.
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).
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.
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.
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).
IPForward=
Configures IP packet forwarding for the system. If enabled,
incoming packets on any network interface will be forwarded
to any other interfaces according to the routing table. Takes
a boolean, or the values "ipv4" or "ipv6", which only enable
IP packet forwarding for the specified address family. This
controls the net.ipv4.ip_forward and
net.ipv6.conf.all.forwarding sysctl options of the network
interface (see IP Sysctl[7] for details about sysctl
options). Defaults to "no".
Note: this setting controls a global kernel option, and does
so one way only: if a network that has this setting enabled
is set up the global setting is turned on. However, it is
never turned off again, even after all networks with this
setting enabled are shut down again.
To allow IP packet forwarding only between specific network
interfaces use a firewall.
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. Takes one of "ipv4",
"ipv6", "both", or "no". Defaults to "no". If enabled, this
automatically sets IPForward= to one of "ipv4", "ipv6" or
"yes".
Note. Any positive boolean values such as "yes" or "true" are
now deprecated. Please use one of the values in the above.
IPv6PrivacyExtensions=
Configures use of stateless temporary addresses that change
over time (see RFC 4941[8], 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. Defaults to "no".
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. The default is to disable RA reception for
bridge devices or when IP forwarding is enabled, and to
enable it otherwise. Cannot be enabled on bond devices and
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[7] 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.
IPv6DuplicateAddressDetection=
Configures the amount of IPv6 Duplicate Address Detection
(DAD) probes to send. When unset, the kernel's default will
be used.
IPv6HopLimit=
Configures IPv6 Hop Limit. 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.
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.
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.
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[9]. When
unset, the kernel's default will be used.
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.
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.
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 DCHPPrefixDelegation= setting and the [IPv6SendRA],
[IPv6Prefix], [IPv6RoutePrefix], and [DHCPPrefixDelegation]
sections for more configuration options.
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.
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.
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.
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).
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.
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.
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.
ConfigureWithoutCarrier=
Takes a boolean. Allows 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.
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.
KeepConfiguration=
Takes a boolean or one of "static", "dhcp-on-stop", "dhcp".
When "static", systemd-networkd will not drop static
addresses and routes on starting up process. When set to
"dhcp-on-stop", systemd-networkd will not drop addresses and
routes on stopping the daemon. When "dhcp", the addresses and
routes provided by a DHCP server will never be dropped even
if the DHCP lease expires. 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 "dhcp"
implies "dhcp-on-stop", and "yes" implies "dhcp" and
"static". Defaults to "dhcp-on-stop" when systemd-networkd is
running in initrd, "yes" when the root filesystem is a
network filesystem, and "no" otherwise.
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.
Peer=
The peer address in a point-to-point connection. Accepts the
same format as the Address= setting.
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.
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.
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.
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".
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.
HomeAddress=
Takes a boolean. Designates this address the "home address"
as defined in RFC 6275[10]. Supported only on IPv6. Defaults
to false.
DuplicateAddressDetection=
Takes one of "ipv4", "ipv6", "both", or "none". When "ipv4",
performs IPv4 Address Conflict Detection. See RFC 5227[11].
When "ipv6", performs IPv6 Duplicate Address Detection. See
RFC 4862[12]. Defaults to "ipv4" for IPv4 link-local
addresses, "ipv6" for IPv6 addresses, and "none" otherwise.
ManageTemporaryAddress=
Takes a boolean. If true the kernel manage temporary
addresses created from this one as template on behalf of
Privacy Extensions RFC 3041[13]. 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.
AddPrefixRoute=
Takes a boolean. When true, the prefix route for the address
is automatically added. Defaults to true.
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 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".
NetLabel=label
This setting provides a method for integrating static and
dynamic network configuration into Linux NetLabel[14]
subsystem rules, used by Linux Security Modules (LSMs)[15]
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[16] 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 hasn't 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".
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.
LinkLayerAddress=
The link layer address (MAC address or IP address) of the
neighbor.
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[17]. Precedence is managed by userspace, and only the
label itself is stored in the kernel.
Label=
The label for the prefix, an unsigned integer in the range
0...4294967294. 0xffffffff is reserved. This setting is
mandatory.
Prefix=
IPv6 prefix is an address with a prefix length, separated by
a slash "/" character. This setting is mandatory.
An [RoutingPolicyRule] section accepts the following settings.
Specify several [RoutingPolicyRule] sections to configure several
rules.
TypeOfService=
Takes a number between 0 and 255 that specifies the type of
service to match.
From=
Specifies the source address prefix to match. Possibly
followed by a slash and the prefix length.
To=
Specifies the destination address prefix to match. Possibly
followed by a slash and the prefix length.
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".
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".
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.
IncomingInterface=
Specifies incoming device to match. If the interface is
loopback, the rule only matches packets originating from this
host.
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.
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.
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.
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.
InvertRule=
A boolean. Specifies whether the rule is to be inverted.
Defaults to false.
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".
User=
Takes a username, a user ID, or a range of user IDs separated
by a dash. Defaults to unset.
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.
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.
Type=
Specifies Routing Policy Database (RPDB) rule type. Takes one
of "blackhole", "unreachable" or "prohibit".
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. If unspecified, then automatically chosen by
kernel.
Gateway=
As in the [Network] section.
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".
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".
Blackhole=
Takes a boolean. If enabled, packets to the corresponding
routes are discarded silently, and Gateway= cannot be
specified. Defaults to "no".
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.
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.
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".
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.
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.
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.
IPv6Preference=
Specifies the route preference as defined in RFC 4191[18] 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.
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 doesn't 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.
PreferredSource=
The preferred source address of the route. The address must
be in the format described in inet_pton(3).
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".
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".
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".
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.
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.
QuickAck=
Takes a boolean. When true enables TCP quick ack mode for the
route. When unset, the kernel's default will be used.
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.
TTLPropagate=
Takes a boolean. When true enables TTL propagation at Label
Switched Path (LSP) egress. When unset, the kernel's default
will be used.
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.
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.
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.
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.
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.
The [DHCPv4] section configures the DHCPv4 client, if it is
enabled with the DHCP= setting described above:
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.
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.
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[19].
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.
ClientIdentifier=
The DHCPv4 client identifier to use. Takes one of mac, duid
or duid-only. 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 (see below), is used. If
set to duid-only, only DUID is used, this may not be RFC
compliant, but some setups may require to use this. Defaults
to duid.
VendorClassIdentifier=
The vendor class identifier used to identify vendor type and
configuration.
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.
DUIDType=
Override the global DUIDType= setting for this network. See
networkd.conf(5) for a description of possible values.
DUIDRawData=
Override the global DUIDRawData= setting for this network.
See networkd.conf(5) for a description of possible values.
IAID=
The DHCP Identity Association Identifier (IAID) for the
interface, a 32-bit unsigned integer.
Anonymize=
Takes a boolean. When true, the options sent to the DHCP
server will follow the RFC 7844[20] (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, SendHostname=, ClientIdentifier=,
VendorClassIdentifier=, UserClass=, RequestOptions=,
SendOption=, SendVendorOption=, and MUDURL= are 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.
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.
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[21]. This setting can be specified multiple times. If
an empty string is specified, then all options specified
earlier are cleared. Defaults to unset.
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[21]. This setting can be specified multiple times. If
an empty string is specified, then all options specified
earlier are cleared. Defaults to unset.
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".
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.
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).
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.
UseNTP=
When true (the default), the NTP servers received from the
DHCP server will be used by systemd-timesyncd.service.
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.
UseSIP=
When true (the default), the SIP servers received from the
DHCP server will be collected and made available to client
programs.
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".
UseHostname=
When true (the default), the hostname received from the DHCP
server will be set as the transient hostname of the system.
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 "~".
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).
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.
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.
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.
RouteMTUBytes=
Specifies the MTU for the DHCP routes. Please see the [Route]
section for further details.
UseGateway=
When true, the gateway will be requested from the DHCP server
and added to the routing table with a metric of 1024, and a
scope of link. When unset, the value specified with
UseRoutes= is used.
UseTimezone=
When true, the timezone received from the DHCP server will be
set as timezone of the local system. Defaults to false.
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[22]. Defaults to
false.
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.
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.
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.
ListenPort=
Set the port from which the DHCP client packets originate.
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.
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.
SendRelease=
When true, the DHCPv4 client sends a DHCP release packet when
it stops. Defaults to true.
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[11]. Defaults to false.
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.
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.
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.
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[21]. This setting
can be specified multiple times. If an empty string is
specified, then all options specified earlier are cleared.
Defaults to unset.
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[21]. 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.
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.
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.
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[23] for details. Defaults to
true, and the two-message exchange will be used if the server
support it.
UseAddress=
When true (the default), the IP addresses provided by the
DHCPv6 server will be assigned.
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[24].
UseDNS=, UseNTP=, UseHostname=, UseDomains=, NetLabel=
As in the [DHCPv4] section.
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.
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".
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[25], section 2.5.4), in which case the allowed value
is hexadecimal, from 0 to 0x7fffffffffffffff inclusive.
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.
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.
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.
ManageTemporaryAddress=
As in the [Address] section, but defaults to true.
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.
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.
The [IPv6AcceptRA] section configures the IPv6 Router
Advertisement (RA) client, if it is enabled with the
IPv6AcceptRA= setting described above:
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.
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.
prefixstable[:ADDRESS][,UUID]
The algorithm specified in RFC 7217[26] 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.
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::
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).
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).
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.
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".
UseMTU=
Takes a boolean. When true, the MTU received in the Router
Advertisement will be used. Defaults to true.
UseGateway=
When true (the default), the router address will be
configured as the default gateway.
UseRoutePrefix=
When true (the default), the routes corresponding to the
route prefixes received in the Router Advertisement will be
configured.
UseAutonomousPrefix=
When true (the default), the autonomous prefix received in
the Router Advertisement will be used and take precedence
over any statically configured ones.
UseOnLinkPrefix=
When true (the default), the onlink prefix received in the
Router Advertisement will be used and takes precedence over
any statically configured ones.
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.
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.
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.
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.
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.
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.
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.
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.
The [DHCPServer] section contains settings for the DHCP server,
if enabled via the DHCPServer= option described above:
ServerAddress=
Specifies server address for the DHCP server. Takes an IPv4
address with prefix length, for example 192.168.0.1/24. This
setting may be useful when the link on which the DHCP server
is running has multiple static addresses. When unset, one of
static addresses in the link will be automatically selected.
Defaults to unset.
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.
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.
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".
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.
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=.
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.
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.
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[27] for
more details. Defaults to unset.
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[28] 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.
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[28] for more details.
Defaults to unset.
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[21]. This setting
can be specified multiple times. If an empty string is
specified, then all options specified earlier are cleared.
Defaults to unset.
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[21]. This setting can be
specified multiple times. If an empty string is specified,
then all options specified earlier are cleared. Defaults to
unset.
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".
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[29]. The address is the address of DHCP
server or another relay agent to forward DHCP messages to and
from.
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.
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.
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.
Address=
The IPv4 address that should be assigned to the device that
was matched with MACAddress=. This key is mandatory.
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.
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).
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[18] for details.
Defaults to "medium".
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".
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.
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.
DNSLifetimeSec=
Lifetime in seconds for the DNS server addresses listed in
DNS= and search domains listed in Domains=. Defaults to 3600
seconds (one hour).
One or more [IPv6Prefix] sections contain the IPv6 prefixes that
are announced via Router Advertisements. See RFC 4861[30] 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.
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.
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).
Assign=
Takes a boolean. When true, adds an address from the prefix.
Default to false.
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.
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.
One or more [IPv6RoutePrefix] sections contain the IPv6 prefix
routes that are announced via Router Advertisements. See RFC
4191[18] 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.
LifetimeSec=
Lifetime for the route prefix measured in seconds.
LifetimeSec= defaults to 3600 seconds (one hour).
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.
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.
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.
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.
Learning=
Takes a boolean. Configures whether MAC address learning is
enabled for this port. When unset, the kernel's default will
be used.
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.
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.
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.
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.
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.
ProxyARP=
Takes a boolean. Configures whether proxy ARP to be enabled
on this port. When unset, the kernel's default will be used.
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.
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.
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.
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. Networkd
does not set any default, meaning the kernel default value of
32 is used.
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.
Destination=
Takes an IP address of the destination VXLAN tunnel endpoint.
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.
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.
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's valid if the
referenced device is a VXLAN type device and has route
shortcircuit enabled. Defaults to "self".
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.
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 or IPv6 multicast group address to add.
This setting is mandatory.
VLANId=
The VLAN ID for the new entry. Valid ranges are 0 (no VLAN)
to 4094. Optional, defaults to 0.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
OneShot=
Takes a boolean. When "yes", one-shot mode is enabled. When
unset, the kernel's default will be used.
PresumeAck=
Takes a boolean. When "yes", the interface will ignore
missing CAN ACKs. When unset, the kernel's default will be
used.
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.
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.
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.
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.
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–Oxffff 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.
DelayJitterSec=
Specifies the chosen delay to be added to the packets
outgoing to the network interface. Defaults to unset.
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.
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.
DuplicateRate=
Specifies that the chosen percent of packets is duplicated
before queuing them. Takes a percentage value, suffixed with
"%". Defaults to unset.
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–Oxffff 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.
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.
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.
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.
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.
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.
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.
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–Oxffff 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.
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–Oxffff 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.
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–Oxffff 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.
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–Oxffff 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.
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–Oxffff 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.
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–Oxffff 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.
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–Oxffff 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.
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–Oxffff 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–Oxffff 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.
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.
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.
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.
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.
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.
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.
src-host
Flows are defined only by source address. Equivalent to
the "srchost" option for tc qdisc command. See also
tc-cake(8).
dst-host
Flows are defined only by destination address. Equivalent
to the "dsthost" option for tc qdisc command. See also
tc-cake(8).
hosts
Flows are defined by source-destination host pairs.
Equivalent to the same option for tc qdisc command. See
also tc-cake(8).
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).
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).
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).
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).
Defaults to unset and the kernel's default is used.
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.
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.
precedence
Enables priority queueing based on the legacy
interpretation of TOS "Precedence" field. Use of this
preset on the modern Internet is firmly discouraged.
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.
diffserv4
Enables priority queueing based on the Differentiated
Service ("DiffServ") field with four tins: Background
Traffic, Best Effort, Streaming Media, and Latency
Sensitive.
diffserv3
Enables priority queueing based on the Differentiated
Service ("DiffServ") field with three tins: Background
Traffic, Best Effort, and Latency Sensitive.
Defaults to unset, and the kernel's default is used.
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.
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.
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.
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.
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.
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–Oxffff 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.
TargetSec=
Takes a timespan. Specifies the acceptable minimum
standing/persistent queue delay. Defaults to unset and
kernel's default is used.
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.
ECN=
Takes a boolean. This can be used to mark packets instead of
dropping them. Defaults to unset and kernel's default is
used.
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.
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–Oxffff 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–Oxffff 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–Oxffff 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.
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–Oxffff 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=.
StrictBands=
Specifies the number of bands that should be created in
strict mode. An unsigned integer in the range 1...16.
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.
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.
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–Oxffff 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.
DefaultVirtualQueue=
Specifies the number of default virtual queue. This must be
less than VirtualQueue=. Defaults to unset and kernel's
default is used.
GenericRIO=
Takes a boolean. It turns on the RIO-like buffering scheme.
Defaults to unset and kernel's default is used.
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–Oxffff 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.
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.
Flows=
Specifies the number of flows into which the incoming packets
are classified. Defaults to unset and kernel's default is
used.
TargetSec=
Takes a timespan. Specifies the acceptable minimum
standing/persistent queue delay. Defaults to unset and
kernel's default is used.
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.
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.
ECN=
Takes a boolean. This can be used to mark packets instead of
dropping them. Defaults to unset and kernel's default is
used.
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.
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–Oxffff 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.
FlowLimit=
Specifies the hard limit on the maximum number of packets
queued per flow. Defaults to unset and kernel's default is
used.
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.
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.
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.
Buckets=
Specifies the size of the hash table used for flow lookups.
Defaults to unset and kernel's default is used.
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.
Pacing=
Takes a boolean, and enables or disables flow pacing.
Defaults to unset and kernel's default is used.
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.
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–Oxffff 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.
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–Oxffff 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.
RateToQuantum=
Takes an unsigned integer. The DRR quantums are calculated by
dividing the value configured in Rate= by RateToQuantum=.
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–Oxffff 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–Oxffff 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.
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.
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.
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.
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.
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.
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.
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.
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–Oxffff 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.
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–Oxffff 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–Oxffff 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–Oxffff 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.
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.
The [BridgeVLAN] section manages the VLAN ID configuration of a
bridge port and accepts the following keys. Specify several
[BridgeVLAN] sections to configure several VLAN entries. The
VLANFiltering= option has to be enabled, see the [Bridge] section
in systemd.netdev(5).
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.
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.
PVID=
The Port VLAN ID specified here is assigned to all untagged
frames at ingress. PVID= can be used only once. Configuring
PVID= implicates the use of VLAN= above and will enable the
VLAN ID for ingress as well.
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 below setting is optional, to also assign an address in the delegated prefix
# to the upstream interface. If not necessary, then comment out the line below and
# the [DHCPPrefixDelegation] section.
DHCPPrefixDelegation=yes
# If the upstream network provides Router Advertisement with Managed bit set,
# then comment out the line below and WithoutRA= setting in the [DHCPv6] section.
IPv6AcceptRA=no
[DHCPv6]
WithoutRA=solicit
[DHCPPrefixDelegation]
UplinkInterface=:self
SubnetId=0
Announce=no
# /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=100-200
[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 won't 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. System and Service Credentials
https://systemd.io/CREDENTIALS
2. Link-Local Multicast Name Resolution
https://tools.ietf.org/html/rfc4795
3. Multicast DNS
https://tools.ietf.org/html/rfc6762
4. DNS-over-TLS
https://tools.ietf.org/html/rfc7858
5. DNSSEC
https://tools.ietf.org/html/rfc4033
6. IEEE 802.1AB-2016
https://standards.ieee.org/findstds/standard/802.1AB-2016.html
7. IP Sysctl
https://docs.kernel.org/networking/ip-sysctl.html
8. RFC 4941
https://tools.ietf.org/html/rfc4941
9. RFC 1027
https://tools.ietf.org/html/rfc1027
10. RFC 6275
https://tools.ietf.org/html/rfc6275
11. RFC 5227
https://tools.ietf.org/html/rfc5227
12. RFC 4862
https://tools.ietf.org/html/rfc4862
13. RFC 3041
https://tools.ietf.org/html/rfc3041
14. NetLabel
https://docs.kernel.org/netlabel/index.html
15. Linux Security Modules (LSMs)
https://en.wikipedia.org/wiki/Linux_Security_Modules
16. NetLabel Fallback Peer Labeling
https://github.com/SELinuxProject/selinux-notebook/blob/main/src/network_support.md
17. RFC 3484
https://tools.ietf.org/html/rfc3484
18. RFC 4191
https://tools.ietf.org/html/rfc4191
19. RFC 8520
https://tools.ietf.org/html/rfc8520
20. RFC 7844
https://tools.ietf.org/html/rfc7844
21. C-style escapes
https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences
22. RFC 5969
https://tools.ietf.org/html/rfc5969
23. RFC 3315
https://tools.ietf.org/html/rfc3315#section-17.2.1
24. RFC 8415
https://www.rfc-editor.org/rfc/rfc8415.html#section-6.3
25. RFC 4291
https://tools.ietf.org/html/rfc4291#section-2.5.4
26. RFC 7217
https://tools.ietf.org/html/rfc7217
27. RFC 2131
https://www.rfc-editor.org/rfc/rfc2131.html
28. RFC 2132
https://www.rfc-editor.org/rfc/rfc2132.html
29. RFC 1542
https://tools.ietf.org/html/rfc1542
30. 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 2022-12-17. (At that
time, the date of the most recent commit that was found in the
repository was 2022-12-16.) 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 252 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-networkd.service(8), systemd-network-generator.service(8), systemd-resolved.service(8), systemd-timesyncd.service(8)
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