I have a similar problem, But instead of having 2 network cards I have one card using IP aliasing ( two subnets on the same card/network, one for DSL and the second local 192.168.0.x).
as soon as I start ipmasq I cannot ping beyond the local subnet of each card, thus I cannot access the DNS server, thus I cannot ping or surf out side the to subnets. I tried to start ipmasq after after the two network are initialized, but as soon as ipmasq start I loose the DNS server and access beyond the local net. I have the latest potato system using kernel 2.2.7 I have the latest potato version of ipmask. Does any one have any idea how to solve/debug this problem? Is this problem occurring because ipmasq make the second non local net a firewall? If that is the case how can I have ipmasq apply only to the subnet 192.168.0.x and not to the DSL subnet.? how can I have ipmasq apply to eth0 ( 192.168.0.x) and not to the subnet of eth0:0 (DSL subnet) What does ipmasq do? I have a second linux computer running kernel 2.2.1 (hybrid system of sling hamm and potato). I do not use ipmasq. I have ipalias working correctly with masquerading (apply the firewall only to the local subnet). I use ipchain to apply the rules. -Thanks Oz Dror
