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ip-netns


SYNOPSIS

       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


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
       /var/run/netns/NAME that can be opened. The file descriptor resulting
       from opening /var/run/netns/NAME refers to the specified network names-
       pace. 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 names-
       pace 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
              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 names-
              pace.

              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 pre-
              vent 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 net-
              work 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 names-
              pace.

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

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

              This command watches network namespace name addition and dele-
              tion 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 names-
              pace. This command displays nsid of the current network names-
              pace and provides the corresponding iproute2 netns name (from
              /var/run/netns) if any.


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.


SEE ALSO

       ip(8)


AUTHOR

       Original Manpage by Eric W. Biederman


iproute2 16 Jan 2013 IP-NETNS(8)



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