ip-netns(8) — Linux manual page


IP-NETNS(8)                         Linux                        IP-NETNS(8)

NAME         top

       ip-netns - process network namespace management

SYNOPSIS         top

       ip [ OPTIONS ] netns  { COMMAND | help }

       ip netns [ list ]

       ip netns add NETNSNAME

       ip netns attach NETNSNAME PID

       ip [-all] netns del [ NETNSNAME ]

       ip netns set NETNSNAME NETNSID

       NETNSID := auto | POSITIVE-INT

       ip netns identify [ PID ]

       ip netns pids NETNSNAME

       ip [-all] netns exec [ NETNSNAME ] command...

       ip netns monitor

       ip netns list-id [ target-nsid POSITIVE-INT ] [ nsid POSITIVE-INT ]

DESCRIPTION         top

       A network namespace is logically another copy of the network stack,
       with its own routes, firewall rules, and network devices.

       By default a process inherits its network namespace from its parent.
       Initially all the processes share the same default network namespace
       from the init process.

       By convention a named network namespace is an object at
       /var/run/netns/NAME that can be opened. The file descriptor resulting
       from opening /var/run/netns/NAME refers to the specified network
       namespace. Holding that file descriptor open keeps the network
       namespace alive. The file descriptor can be used with the setns(2)
       system call to change the network namespace associated with a task.

       For applications that are aware of network namespaces, the convention
       is to look for global network configuration files first in
       /etc/netns/NAME/ then in /etc/.  For example, if you want a different
       version of /etc/resolv.conf for a network namespace used to isolate
       your vpn you would name it /etc/netns/myvpn/resolv.conf.

       ip netns exec automates handling of this configuration, file
       convention for network namespace unaware applications, by creating a
       mount namespace and bind mounting all of the per network namespace
       configure files into their traditional location in /etc.

       ip netns list - show all of the named network namespaces

              This command displays all of the network namespaces in

       ip netns add NAME - create a new named network namespace

              If NAME is available in /var/run/netns this command creates a
              new network namespace and assigns NAME.

       ip netns attach NAME PID - create a new named network namespace

              If NAME is available in /var/run/netns this command attaches
              the network namespace of the process PID to NAME as if it were
              created with ip netns.

       ip [-all] netns delete [ NAME ] - delete the name of a network

              If NAME is present in /var/run/netns it is umounted and the
              mount point is removed. If this is the last user of the
              network namespace the network namespace will be freed and all
              physical devices will be moved to the default one, otherwise
              the network namespace persists until it has no more users. ip
              netns delete may fail if the mount point is in use in another
              mount namespace.

              If -all option was specified then all the network namespace
              names will be removed.

              It is possible to lose the physical device when it was moved
              to netns and then this netns was deleted with a running

                 $ ip netns add net0
                 $ ip link set dev eth0 netns net0
                 $ ip netns exec net0 SOME_PROCESS_IN_BACKGROUND
                 $ ip netns del net0

              and eth0 will appear in the default netns only after
              SOME_PROCESS_IN_BACKGROUND will exit or will be killed. To
              prevent this the processes running in net0 should be killed
              before deleting the netns:

                 $ ip netns pids net0 | xargs kill
                 $ ip netns del net0

       ip netns set NAME NETNSID - assign an id to a peer network namespace

              This command assigns a id to a peer network namespace. This id
              is valid only in the current network namespace.  If the
              keyword "auto" is specified an available nsid will be chosen.
              This id will be used by the kernel in some netlink messages.
              If no id is assigned when the kernel needs it, it will be
              automatically assigned by the kernel.  Once it is assigned,
              it's not possible to change it.

       ip netns identify [PID] - Report network namespaces names for process

              This command walks through /var/run/netns and finds all the
              network namespace names for network namespace of the specified
              process, if PID is not specified then the current process will
              be used.

       ip netns pids NAME - Report processes in the named network namespace

              This command walks through proc and finds all of the process
              who have the named network namespace as their primary network

       ip [-all] netns exec [ NAME ] cmd ... - Run cmd in the named network

              This command allows applications that are network namespace
              unaware to be run in something other than the default network
              namespace with all of the configuration for the specified
              network namespace appearing in the customary global locations.
              A network namespace and bind mounts are used to move files
              from their network namespace specific location to their
              default locations without affecting other processes.

              If -all option was specified then cmd will be executed
              synchronously on the each named network namespace even if cmd
              fails on some of them. Network namespace name is printed on
              each cmd executing.

       ip netns monitor - Report as network namespace names are added and

              This command watches network namespace name addition and
              deletion events and prints a line for each event it sees.

       ip netns list-id [target-nsid POSITIVE-INT] [nsid POSITIVE-INT] -
       list network namespace ids (nsid)

              Network namespace ids are used to identify a peer network
              namespace. This command displays nsids of the current network
              namespace and provides the corresponding iproute2 netns name
              (from /var/run/netns) if any.

              The target-nsid option enables to display nsids of the
              specified network namespace instead of the current network
              namespace. This target-nsid is a nsid from the current network

              The nsid option enables to display only this nsid. It is a
              nsid from the current network namespace. In combination with
              the target-nsid option, it enables to convert a specific nsid
              from the current network namespace to a nsid of the target-
              nsid network namespace.

EXAMPLES         top

       ip netns list
              Shows the list of current named network namespaces

       ip netns add vpn
              Creates a network namespace and names it vpn

       ip netns exec vpn ip link set lo up
              Bring up the loopback interface in the vpn network namespace.

       ip netns add foo
       ip netns add bar
       ip netns set foo 12
       ip netns set bar 13
       ip -n foo netns set foo 22
       ip -n foo netns set bar 23
       ip -n bar netns set foo 32
       ip -n bar netns set bar 33
       ip netns list-id target-nsid 12
              Shows the list of nsids from the network namespace foo.
       ip netns list-id target-nsid 12 nsid 13
              Get nsid of bar from the network namespace foo (result is 23).

SEE ALSO         top


AUTHOR         top

       Original Manpage by Eric W. Biederman
       Manpage revised by Nicolas Dichtel <nicolas.dichtel@6wind.com>

COLOPHON         top

       This page is part of the iproute2 (utilities for controlling TCP/IP
       networking and traffic) project.  Information about the project can
       be found at 
       If you have a bug report for this manual page, send it to
       netdev@vger.kernel.org, shemminger@osdl.org.  This page was obtained
       from the project's upstream Git repository
       ⟨https://git.kernel.org/pub/scm/network/iproute2/iproute2.git⟩ on
       2020-09-18.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-09-14.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
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       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

iproute2                         16 Jan 2013                     IP-NETNS(8)

Pages that refer to this page: systemd-nspawn(1)veth(4)network_namespaces(7)ip(8)ip-link(8)