|
HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|
|
NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | AUTHOR | COLOPHON |
|
|
|
IP-NETNS(8) Linux IP-NETNS(8)
ip-netns - process network namespace management
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
]
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.
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).
ip(8)
Original Manpage by Eric W. Biederman
Manpage revised by Nicolas Dichtel <[email protected]>
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
[email protected], [email protected]. This page was
obtained from the project's upstream Git repository
⟨https://git.kernel.org/pub/scm/network/iproute2/iproute2.git⟩ on
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-08-08.) 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 protected]
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), lsns(8)
|
HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|