The text below was the original README.  A more elaborate howto can be found at
http://thomer.com/icmptx/


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an icmp tunnel application based on itunnel and vtun.

it.c		- modified itunnel part (pretty straightforward)
tun_dev.c	- tun/tap part from vtun (copy)

to run it, make sure you have tuntap in kernel (with 2.6, the driver is 'tun',
not sure if it works with older kernels - i removed older driver support).

create a tunnel on a server (to a dummy address) with:
./create_tun dummy_address

set the link up with ifconfig or iproute2 ip, set up routes and everything else
as needed (set MTU!):
ifconfig tun0 mtu 1400 192.168.3.1
route add 192.168.3.2 tun0

create tunnel from client:
./create_tun server

set the link up, routes as needed and so on:
ifconfig tun0 mtu 1400 192.168.3.2
route add 192.168.3.1 tun0
route add default gw 192.168.3.1

the MTU should be set to 1400 (it's defined in create_tun.c) or to anything
that can be sent as a payload of a single ICMP packet (changing create_tun.c
accordingly).

Enjoy.