NetBSD-5.0.2/share/man/man4/etherip.4

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.\"     $NetBSD: etherip.4,v 1.7 2008/05/04 19:43:05 martin Exp $
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.\" Copyright (c) 2006, Hans Rosenfeld <rosenfeld@grumpf.hope-2000.org>.
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.Dd November 23, 2006
.Dt ETHERIP 4
.Os
.Sh NAME
.Nm etherip
.Nd EtherIP tunneling device
.Sh SYNOPSIS
.Cd "pseudo-device etherip"
.Sh DESCRIPTION
The
.Nm
interface is a tunneling pseudo device for Ethernet frames.
It can tunnel Ethernet traffic over IPv4 and IPv6 using the EtherIP
protocol specified in RFC 3378.
.Pp
The only difference between an
.Nm
interface and a real Ethernet interface is that there is an IP tunnel
instead of a wire.
Therefore, to use
.Nm
the administrator must first create the interface and then configure
protocol and addresses used for the outer header.
This can be done by using
.Xr ifconfig 8
.Cm create
and
.Cm tunnel
subcommands, or
.Dv SIOCIFCREATE
and
.Dv SIOCSLIFPHYADDR
ioctls.
.Ss Packet format
Ethernet frames are prepended with a EtherIP header as described by
RFC 3378.
The resulting EtherIP packets will be encapsulated in an
outer packet, which may be either an IPv4 or IPv6 packet, with IP
protocol number 97.
.Ss Ethernet address
When a
.Nm
device is created, it is assigned an Ethernet address
of the form f2:0b:a5:xx:xx:xx.
This address can later be changed through a sysctl node.
.Pp
The sysctl node is net.link.etherip.\*[Lt]iface\*[Gt].
Any string of six colon-separated hexadecimal numbers will be accepted.
Reading that node will provide a string representation of the current
Ethernet address.
.Ss Security
The EtherIP header of incoming packets is not checked for
validity.
This is because there seems to be some confusion about how
such a header has to look like.
For outgoing packets, the header is set up the same way as done in
.Ox ,
.Fx ,
and Linux to be compatible with those systems.
.Ss Converting from previous implementation
A tunnel configured for the previous (undocumented) implementation
will work with just renaming the device from gif to
.Nm .
.Sh SEE ALSO
.Xr bridge 4 ,
.Xr gif 4 ,
.Xr inet 4 ,
.Xr inet6 4 ,
.Xr tap 4 ,
.Xr ifconfig 8
.\"
.Sh HISTORY
The
.Nm
device first appeared in
.Nx 4.0 ,
it is based on
.Xr tap 4 ,
.Xr gif 4 ,
and the former gif-based EtherIP implementation ported from
.Ox .
.\"
.Sh BUGS
Probably many.
There is lots of code duplication between
.Nm ,
.Xr tap 4 ,
.Xr gif 4 ,
and probably other tunnelling drivers which should be cleaned up.