Hi, Apologies for the cross-posting; I'm not sure whether this is a firewall or routing issue, or both! I have four network cards, detailed below. eth0 and eth3 connect to my ISPs, and eth1 and eth2 connect to local networks. I want to route all traffic from eth2 to eth0, and from eth1 to eth3. However, I am having a few problems with this. eth0 ip: 192.168.100.253/24 gw: 192.168.100.254 (ISP) eth1 ip: 192.168.3.253/22 gw: 192.168.20.253 (eth3) eth2 ip: 192.168.7.253/22 gw: 192.168.100.253 (eth0) eth3 ip: 192.168.20.253/24 gw: 192.168.20.254 (ISP) I have tried setting up routing using these commands: echo "ISP_1" >> /etc/iproute2/rt_tables echo "ISP_2" >> /etc/iproute2/rt_tables ip route add 192.168.4.0/22 dev eth2 src 192.168.7.253 table ISP_1 ip route add default via 192.168.100.253 table ISP_1 ip route add 192.168.0.0/22 dev eth1 src 192.168.3.253 table ISP_2 ip route add default via 192.168.20.253 table ISP_2 ip rule add from 192.168.7.253 table ISP_1 ip rule add from 192.168.3.253 table ISP_2 However, this yielded no success. I have also tried a simple iptables forwarding configuration (without the routing config above): iptables -A FORWARD -i eth0 -o eth2 -j ACCEPT iptables -A FORWARD -i eth2 -o eth0 -j ACCEPT iptables -A FORWARD -i eth1 -o eth3 -j ACCEPT iptables -A FORWARD -i eth3 -o eth1 -j ACCEPT # default policy iptables -P FORWARD DROP Again, with no success. I do have a reasonably complex firewall in place, but no other rules in the FORWARD section of the firewall. I have a number of open ports under INPUT for other services the machine provides, and nothing under OUTPUT. In the NAT section, I have no rules in OUTPUT, a couple of MASQUERADING rules under POSTROUTING, and hundreds of rules under PREROUTING (accepting or denying machines based on their MAC). I've had a few thoughts on this; do I need to have four default gateways configured; one for each network card? And do I need more (or any) forwarding rules in the firewall? I've been struggling with this problem for some time now, and it's really starting to annoy me. I would really appreciate any feedback people could send me. Many thanks, Paul --- Paul Lewis (paul.lewis@xxxxxxxxxxxxxxxxx) Part II Student Department Of Materials University Of Oxford
