mirror of https://github.com/mkerrisk/man-pages
107 lines
3.1 KiB
Groff
107 lines
3.1 KiB
Groff
.\" Copyright (c) 2012 Tomáš Pospíšek (tpo_deb@sourcepole.ch),
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.\" Fri, 03 Nov 2012 22:35:33 +0100
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.\" and Copyright (c) 2012 Eric W. Biederman <ebiederm@xmission.com>
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.\"
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.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public
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.\" License along with this manual; if not, write to the Free
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.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
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.\" USA.
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.\" %%%LICENSE_END
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.\"
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.\"
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.TH VETH 4 2021-03-22 "Linux" "Linux Programmer's Manual"
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.SH NAME
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veth \- Virtual Ethernet Device
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.SH DESCRIPTION
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The
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.B veth
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devices are virtual Ethernet devices.
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They can act as tunnels between network namespaces to create
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a bridge to a physical network device in another namespace,
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but can also be used as standalone network devices.
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.PP
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.B veth
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devices are always created in interconnected pairs.
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A pair can be created using the command:
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.PP
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.in +4n
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.EX
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# ip link add <p1-name> type veth peer name <p2-name>
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.EE
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.in
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.PP
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In the above,
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.I p1-name
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and
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.I p2-name
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are the names assigned to the two connected end points.
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.PP
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Packets transmitted on one device in the pair are immediately received on
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the other device.
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When either devices is down the link state of the pair is down.
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.PP
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.B veth
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device pairs are useful for combining the network
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facilities of the kernel together in interesting ways.
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A particularly interesting use case is to place one end of a
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.B veth
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pair in one network namespace and the other end in another network namespace,
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thus allowing communication between network namespaces.
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To do this, one can provide the
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.B netns
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parameter when creating the interfaces:
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.PP
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.in +4n
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.EX
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# ip link add <p1\-name> netns <p1\-ns> type veth peer <p2\-name> netns <p2\-ns>
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.EE
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.in
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.PP
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or, for an existing
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.B veth
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pair, move one side to the other namespace:
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.PP
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.in +4n
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.EX
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# ip link set <p2\-name> netns <p2\-ns>
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.EE
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.in
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.PP
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.BR ethtool (8)
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can be used to find the peer of a
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.B veth
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network interface, using commands something like:
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.PP
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.in +4n
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.EX
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# \fBip link add ve_A type veth peer name ve_B\fP # Create veth pair
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# \fBethtool \-S ve_A\fP # Discover interface index of peer
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NIC statistics:
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peer_ifindex: 16
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# \fBip link | grep \(aq\(ha16:\(aq\fP # Look up interface
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16: ve_B@ve_A: <BROADCAST,MULTICAST,M\-DOWN> mtu 1500 qdisc ...
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.EE
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.in
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.SH "SEE ALSO"
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.BR clone (2),
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.BR network_namespaces (7),
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.BR ip (8),
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.BR ip\-link (8),
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.BR ip\-netns (8)
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