.\" Copyright (c) 2017 by Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.\"
.TH NETWORK_NAMESPACES 7 2020-06-09 "Linux" "Linux Programmer's Manual"
.SH NAME
network_namespaces \- overview of Linux network namespaces
.SH DESCRIPTION
Network namespaces provide isolation of the system resources associated
with networking: network devices, IPv4 and IPv6 protocol stacks,
IP routing tables, firewall rules, the
.I /proc/net
directory (which is a symbolic link to
.IR /proc/PID/net ),
the
.I /sys/class/net
directory, various files under
.IR /proc/sys/net ,
port numbers (sockets), and so on.
In addition,
network namespaces isolate the UNIX domain abstract socket namespace (see
.BR unix (7)).
.PP
A physical network device can live in exactly one
network namespace.
When a network namespace is freed
(i.e., when the last process in the namespace terminates),
its physical network devices are moved back to the
initial network namespace (not to the parent of the process).
.PP
A virtual network
.RB ( veth (4))
device pair provides a pipe-like abstraction
that can be used to create tunnels between network namespaces,
and can be used to create a bridge to a physical network device
in another namespace.
When a namespace is freed, the
.BR veth (4)
devices that it contains are destroyed.
.PP
Use of network namespaces requires a kernel that is configured with the
.B CONFIG_NET_NS
option.
.\" FIXME .SH EXAMPLES
.SH SEE ALSO
.BR nsenter (1),
.BR unshare (1),
.BR clone (2),
.BR veth (4),
.BR proc (5),
.BR sysfs (5),
.BR namespaces (7),
.BR user_namespaces (7),
.BR brctl (8),
.BR ip (8),
.BR ip\-address (8),
.BR ip\-link (8),
.BR ip\-netns (8),
.BR iptables (8),
.BR ovs\-vsctl (8)