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 networknamespace(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
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
$ 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
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 networknamespace
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 anddeleted
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.
This page is part of the iproute2 (utilities for controlling TCP/IP
networking and traffic) project. Information about the project can
be found at
If you have a bug report for this manual page, send it to
email@example.com, firstname.lastname@example.org. This page was obtained
from the project's upstream Git repository
on 2016-12-10. 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 email@example.com
iproute2 16 Jan 2013 IP-NETNS(8)