ip-netns - process network namespace management


   ip [ OPTIONS ] netns  { COMMAND | help }

   ip netns { list }

   ip netns add NETNSNAME

   ip [-all] netns del [ NETNSNAME ]

   ip netns { set } NETNSNAME NETNSID

   ip netns identify [ PID ]

   ip netns pids NETNSNAME

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

   ip netns monitor

   ip netns list-id


   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 [-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

          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

          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.  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 - list network namespace ids (nsid)

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


   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.




   Original Manpage by Eric W. Biederman


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