Linux Router problem
 

Hi,
i am setting up linux Router that will conect LAN2 with main LAN1. In LAN1 Windows SB server 2000 OS is installed and cisco 675 router used to connect outside. On Linux router I did set up Router table and it seems to work, since i can ping from linux router box any linux box on LAN2 and any PC including Router on LAN1. The problem is when i try to ping from one of the Linux box of LAN2. It can ping the Linux router of LAN2, and Linux router can ping that Linux box, but when the linux box tryies to ping any PC and router on the LAN,1 it stops. The lights on switch are going on and off. There is no message telling that the PC or router it tryies to ping is unreachable. It stops rigth after calliing ping xx.xx.xx.xx command.
either on linux box or router the routing tables is correct since those are exactly from book.
Does anyone has ideas how to troublshoot this problem? ..is there anything else to be configured beside makinig changes in Router table for Linux router?
Thank's
Margots

Are you sure you have the kernel IP forwarding flag set ? Check :

# cat /proc/sys/net/ipv4/ip_forward

If it's not set to 1, do a :

# echo 1 >/proc/sys/net/ipv4/ip_forward


dc

Thank's dcgva,
it was set to zero. Now i did set to one, but it seems it did not solve the problem.

since i can ping router on LAN2 and LAN1 from my linux workstation on Lan2, would it be something to do with browser settings that i have to change because the proxy server is running on LAN2 router. Or there must be something else?

Margots

I had another ongoing problem which is close to the one you are having...
Let me describe what I was attempting and how I fixed it.

Sys A <- NET X -> Sys B <- Net Y -> Sys C

When adding the Network Y, I moved the Sys C from Network X to this new network. I then modified the routing table on system C to use system as a gateway for network X. I also made sure all routing tables were properly set on system B.

pinging the Net X's network card from system C worked... but I couldn't ping system A. In fact, the network topology is more complex than waht is being displayed here. I have two additional switches on each network, doing VLAN on a fiber. I tried to use an additional system to spy the network. I attempted a 'tcpdump' and couldn't see my paquets... Due to a bad configuration in on of the switches, my paquets were blocked and I couldn't see them because my "spy" was connected to a different "branch" of the network.

It took me two days to realize that my paquets did arrive to system A... but couldn't anywhere since the routing table of system A wasn't correct... It didn't know how to send the answer back to network Y. Even worse... my paquets were sent to the default gateway (on another network) from system A.

Though, don't forget to setup the routing table on BOTH ends. I hope it's going to help you :-)

dc