Hello, I have setup linux routers as shown below PC1 R1 R2 R3 R4 PC2 |---------------| |-------| |--------| |--------| |-----------| 192.168.10.2 .1 12.1 12.2 13.1 13.2 16.1 16.2 11.1 11.2 e0 e0 e1 e0 e1 e0 e1 e0 e1 e0 I am able to send traffic from PC1 to PC2 but I am unable to receive the response beyond R3. I am able to set up a bi directional path from R1 to R4 but unbelievably I can't seem to do the same for PC1 and PC2. Response from a ping from PC2 doesn't go beyond e0 of R3. I have the following settings at R3 iptables -F iptables -P INPUT DROP iptables -P FORWARD DROP iptables -A INPUT -i eth0 -d 192.168.11.2 -j ACCEPT iptables -A FORWARD -i eth0 -d 192.168.11.2 -j ACCEPT iptables -A OUTPUT -o eth1 -d 192.168.11.2 -j ACCEPT iptables -A INPUT -i eth1 -d 192.168.10.2 -j ACCEPT iptables -A FORWARD -i eth1 -d 192.168.10.2 -j ACCEPT iptables -A OUTPUT -i eth0 -d 192.168.10.2 -j ACCEPT I have set the default route as route add default gw 192.168.16.2 dev eth1 Using tcpdump I can see the ping response at eth1 of R3 but it doesn't go beyond that. I tried to add another default route for eth0 as route add default gw 192.168.13.1 dev eth0 but then the traffic from PC1 doesn't go beyond eth0. Any help will be most welcome. Thanks in advance.
