IP-NETNS(8)               (16 Jan 2013)               IP-NETNS(8)

     NAME
          ip-netns - process network namespace management

     SYNOPSIS
          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
          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
          /run/netns/NAME that can be opened. The file descriptor
          resulting from opening /run/netns/NAME refers to the speci-
          fied 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

     Page 1                      iproute2            (printed 5/23/22)

     IP-NETNS(8)               (16 Jan 2013)               IP-NETNS(8)

          you want a different version of /etc/resolv.conf for a net-
          work 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

               This command displays all of the network namespaces in
               /run/netns

          ip netns add NAME - create

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

          ip netns attach NAME PID -

               If NAME is available in /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

               If NAME is present in /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 process:

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

     Page 2                      iproute2            (printed 5/23/22)

     IP-NETNS(8)               (16 Jan 2013)               IP-NETNS(8)

               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 -

               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

               This command walks through /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

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

          ip [-all] netns exec [ NAME

               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.

     Page 3                      iproute2            (printed 5/23/22)

     IP-NETNS(8)               (16 Jan 2013)               IP-NETNS(8)

          ip netns monitor - Report as

               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

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

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

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

     EXAMPLES
          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).

     Page 4                      iproute2            (printed 5/23/22)

     IP-NETNS(8)               (16 Jan 2013)               IP-NETNS(8)

     SEE ALSO
          ip(8)

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

     Page 5                      iproute2            (printed 5/23/22)