Greetings: I'm working with the following configuration: Box C +--------+ _/\__/\_ | |(63..a) / \ | Router/+----------( Internet ) |Firewall|aps0 \_ __ _/ +----+---+ \/ \/ eth1|(204..a) | | +--+----+ | | Linux | Box A DMZ------------+----------+-- +-------+ | | +---+---+ 63..b | Linux | 63..c +-------+ Box B Box C is supposed to be a router/firewall for devices on the internal "DMZ" network. Right now I'm just trying to get the routing working before I do the rest. I've started a simple configuration script which does the following: # Add routing rules # ip rule add iif aps0 to 63..a/32 lookup main priority 190 ip rule add iif aps0 to 63..0/29 lookup isdn-dmz priority 200 ip rule add iif eth1 to 204..a/32 lookup main priority 210 ip rule add iif eth1 lookup dmz-isdn priority 220 # Create routing tables # #dmz-isdn table routes ip route add default dev aps0 table dmz-isdn #isdn-dmz table routes ip route add default dev eth1 table isdn-dmz # Make rules/routes active ip route flush cache echo "1" > /proc/sys/net/ipv4/ip_forward echo "1" > /proc/sys/net/ipv4/ip_always_defrag