Provided by: iproute2_4.3.0-1ubuntu3.16.04.5_amd64 bug


       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 /var/run/netns

       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 namespace(s)

              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 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 namespace.

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

              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

              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 deleted

              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