Man have I had rough weekend!!
Can anyone tell my why my gateway is getting back packets with their TTL equal 1? I'm able to ping hosts on the internet using their IP address, but when I try to ping them using their DNS name the DNS Server responds with a ICMP type 11 packet. I don't know why this is happening!! By the way, this gateway is behind two other gateways. I'v searched the Internet for 2 day and haven't found anything, the only thing that I can think of, is to mangle the TTL field of packets, but I want to find a easier solution to this problem. Thanks in advance for you help to this rather annoying problem.

PS:

I don't have any problems with my local network just with the Internet.

You might have a "metric=1" line in your ifconfig setup. Try getting rid of that. It should be in /etc/rc.d somewhere.

I've looked in /etc/rc.d and there is nothing there that is setting metric=1, I tried setting the interfaces manualy using ifconfig, but ifconfig returns SIOCSIFMETRIC: Operation not supported for every interface that a wan't to change. Tnx for your help anyway.

Okey after doing some lengthy research I have found a solution to this rather stupid problem. The problem appeared because my stupid ISP was filtering packets on their gateway with the TTL field lower than the default value!!! Why where they doing this??? simple, because they where trying to get rid of people that NATing on their network. So how did I outwit my ISP? By hack the kernel :-D In the net/ipv4/ip_forward.c source file I commented out the following two line that are responsible for decrementing the TTL field of the packet being forwarded and returning a ICMP message when the TTL field is less or equal to 1:
goto to_many_hoops;
ip_decrease_ttl(iph);
Then I recompiled my kernel and voila, a working gateway!!!!! Hope that this will he somebody in the future.

Peace out...

PS: If you use these instructions please note that you are breaking RFC standards. Every router/gateways has to decrement the TTL field so that packets don't get to live for ever if the start looping continuously because of bad routers.