Okay sorry for the late answer , it was a terriable week and weekend ! My whole ip classes are down bcz My Co Make changes in the network topologey thigs that make me build a tunnel to the cisco router . for unknown reason (possible bcz my class is down) i have noticed strange traffic on my MRTG reports and alot of kernel panic , which make my server goes down without any reason Well i have make alot of changes on my linux hopely when i wake up tommrow it will be up :-) Anyway short brief of stuff i have tried to do , seems not working. i have change the #define IPIP_PROTO from 94 to 4 on /usr/src/linux/include/linux/in.h and recompile the kernel , as Martin thought , but it didnt help . more than that i have got strnage iptables output ;-) when i have run iptables insted of #ip tunnel tunl0: ip/ip remote any local any ttl inherit nopmtudisc i have got #ip tunnel tunl0: unknown/ip remote any local ttl inherit no... i have tried to recompile the iptables with the (94) definination maybe is that work but i have got ioctl error when i have tried to set up the tunnel ;-) i have take future steps and start goes on the ipv4 source code and the tunneling code ;-) i have e-mail to Alan Cox (Mini Ginenus that code the ipv4 in the linux kernel ) i havent got any respond due the fact my mail serv is down for since 9 Januar Any ideas will be greatfully!