NAME
etherip —
EtherIP tunneling
device
SYNOPSIS
pseudo-device etherip
DESCRIPTION
The
etherip 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.
The only difference between an
etherip interface and a real
Ethernet interface is that there is an IP tunnel instead of a wire. Therefore,
to use
etherip the administrator must first create the
interface and then configure protocol and addresses used for the outer header.
This can be done by using
ifconfig(8)
create and
tunnel subcommands, or
SIOCIFCREATE
and
SIOCSLIFPHYADDR
ioctls.
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.
Ethernet address
When a
etherip 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.
The sysctl node is net.link.etherip.<iface>. Any string of six
colon-separated hexadecimal numbers will be accepted. Reading that node will
provide a string representation of the current Ethernet address.
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
OpenBSD,
FreeBSD, and Linux to
be compatible with those systems.
Converting from
previous implementation
A tunnel configured for the previous (undocumented) implementation will work
with just renaming the device from gif to
etherip.
SEE ALSO
bridge(4),
gif(4),
inet(4),
inet6(4),
tap(4),
ifconfig(8)
HISTORY
The
etherip device first appeared in
NetBSD
4.0, it is based on
tap(4),
gif(4), and the former gif-based
EtherIP implementation ported from
OpenBSD.
BUGS
Probably many. There is lots of code duplication between
etherip,
tap(4),
gif(4), and probably other
tunnelling drivers which should be cleaned up.