gif



GIF(4)                       Device Drivers Manual                      GIF(4)


NAME

     gif - generic tunnel interface


SYNOPSIS

     pseudo-device gif


DESCRIPTION

     The gif interface is a generic tunnelling pseudo-device for IPv4 and
     IPv6.  It can tunnel IPv[46] over IPv[46] with behavior mainly based on
     RFC 4213 IPv6-over-IPv4, for a total of four possible combinations.

     A gif interface can be created at runtime using the ifconfig gifN create
     command or by setting up a hostname.if(5) configuration file for
     netstart(8).

     The gif interface must be configured with the addresses used for the
     outer header.  This can be done by using ifconfig(8)'s tunnel command
     (which uses the SIOCSIFPHYADDR ioctl).

     The addresses of the inner header must be configured by using ifconfig(8)
     in the normal way.  The routing table can be used to direct packets
     toward the gif interface.


SEE ALSO

     sysctl(3), etherip(4), inet(4), inet6(4), ipsec(4), hostname.if(5),
     ifconfig(8), netstart(8)


STANDARDS

     E. Nordmark and R. Gilligan, Basic Transition Mechanisms for IPv6 Hosts
     and Routers, RFC 4213, October 2005.


HISTORY

     The gif device first appeared in WIDE hydrangea IPv6 kit.

     Previously, gif supported RFC 3378 EtherIP tunnels over bridge(4)
     interfaces.  This is now handled by etherip(4).


BUGS

     There are many tunnelling protocol specifications, defined differently
     from each other.  gif may not interoperate with peers which are based on
     different specifications, and are picky about outer header fields.  For
     example, you cannot usually use gif to talk with IPsec devices that use
     IPsec tunnel mode.

     The current code does not check if the ingress address (outer source
     address) configured to gif makes sense.  Make sure to configure an
     address which belongs to your node.  Otherwise, your node will not be
     able to receive packets from the peer, and your node will generate
     packets with a spoofed source address.

     If the outer protocol is IPv6, path MTU discovery for encapsulated packet
     may affect communication over the interface.

OpenBSD 6.2                      June 7, 2016                      OpenBSD 6.2

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