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GIF(4)		       FreeBSD Kernel Interfaces Manual			GIF(4)

     gif -- generic tunnel interface

     pseudo-device gif

     The gif interface is a generic tunnelling pseudo-device.  It can tunnel
     IPv4, IPv6, and MPLS over IPv4 and	IPv6, with behavior mainly based on
     RFC 4213 IPv6-over-IPv4.

     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

     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 SIOCSLIFPHYADDR 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 to-
     ward the gif interface.

     sysctl(2),	etherip(4), gre(4), inet(4), inet6(4), ipsec(4),
     hostname.if(5), ifconfig(8), netstart(8)

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

     T.	Worster, Y. Rekhter, and E. Rosen, Encapsulating MPLS in IP or Generic
     Routing Encapsulation (GRE), RFC 4023, March 2005.

     The gif device first appeared in WIDE hydrangea IPv6 kit.

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

     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	ad-
     dress 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.

FreeBSD	13.0			 July 11, 2018			  FreeBSD 13.0


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