network_namespaces(7) [linux man page]

NETWORK_NAMESPACES(7)					     Linux Programmer's Manual					     NETWORK_NAMESPACES(7)

NAME

       network_namespaces - overview of Linux network namespaces

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 /proc/net directory (which is a symbolic link to /proc/PID/net), the /sys/class/net directory,  various
       files  under  /proc/sys/net,  port  numbers  (sockets), and so on.  In addition, network namespaces isolate the UNIX domain abstract socket
       namespace (see unix(7)).

       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).

       A virtual network (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 veth(4) devices  that	it
       contains are destroyed.

       Use of network namespaces requires a kernel that is configured with the CONFIG_NET_NS option.

SEE ALSO

       nsenter(1),  unshare(1),  clone(2),  veth(4),  proc(5),	sysfs(5),  namespaces(7),  user_namespaces(7), brctl(8), ip(8), ip-address(8), ip-
       link(8), ip-netns(8), iptables(8), ovs-vsctl(8)

Linux								    2018-02-02						     NETWORK_NAMESPACES(7)

veth(4) 						     Linux Programmer's Manual							   veth(4)

NAME

       veth - Virtual Ethernet Device

DESCRIPTION

       The veth devices are virtual Ethernet devices.  They can act as tunnels between network namespaces to create a bridge to a physical network
       device in another namespace, but can also be used as standalone network devices.

       veth devices are always created in interconnected pairs.  A pair can be created using the command:

	   # ip link add <p1-name> type veth peer name <p2-name>

       In the above, p1-name and p2-name are the names assigned to the two connected end points.

       Packets transmitted on one device in the pair are immediately received on the other device.  When either devices is down the link state	of
       the pair is down.

       veth  device  pairs are useful for combining the network facilities of the kernel together in interesting ways.	A particularly interesting
       use case is to place one end of a veth pair in one network namespace and the other end in another network namespace, thus allowing communi-
       cation between network namespaces.  To do this, one first creates the veth device as above and then moves one side of the pair to the other
       namespace:

	   # ip link set <p2-name> netns <p2-namespace>

       ethtool(8) can be used to find the peer of a veth network interface, using commands something like:

	   # ip link add ve_A type veth peer name ve_B	 # Create veth pair
	   # ethtool -S ve_A	     # Discover interface index of peer
	   NIC statistics:
		peer_ifindex: 16
	   # ip link | grep '^16:'   # Look up interface
	   16: ve_B@ve_A: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc ...

SEE ALSO

       clone(2), network_namespaces(7), ip(8), ip-link(8), ip-netns(8)

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

Linux								    2018-02-02								   veth(4)