I setup a PC (with RedHat 9.2) as a router. I did the following procedures to enable route (packet forwarding)

1. edit /etc/sysctl.conf and net.ipv4.ip_forward = 1
2. edit /etc/sysconfig/network and FORWARD_IPV4=true

I have two ethernet interface (eth0 and eth1). I connected to eth0 to a host PC and eth1 to a wireless router (connect the cable internet).

host(pc) -- eth0 <---> eth1 -- wireless router -- cable Internet.

I ran /sbin/route and all the routes setup as expected. I tried ping from host to wireless router . I also turned on ethereal on eth0 and eth1. I captured packet received from eth0, but ICMP packet did not forward to eth1.

Questions,

1. Do I have to run more setup on my Linux router (Redhat PC)?
2. How can I debug the packet forwarding issues? I ran tcpdump and ethereal already, any more tools?

Thanks

do you have the MASQUERADE rules in your iptables?

iptables -A POSTROUTING -t nat -o eth1 -j SNAT --to <ip-of-your-eth1>

www.netfilter.org

sl mritch.