ip-netns(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | AUTHOR | COLOPHON

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
              /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 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
       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.
              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 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 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 deleted

              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 namespace.

              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

       ip(8)

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 
       ⟨http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2⟩.
       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
       2021-04-01.  (At that time, the date of the most recent commit
       that was found in the repository was 2021-03-22.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

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)