Fredrik Ax wrote: > Hi guys, > > I'm a pretty experienced Linux / network developer and administrator, > but I can't get my head around this one. > > The long story is that I have a box used as router/fw/proxy running > Debian Squeeze with a customized 2.6.32 x86_64 kernel having three > interfaces (eth2,eth3,eth4) on the same external subnet. One of the > interfaces is used for doing masquerading of other > subnets. Masquerading (not snat) is chosen because the interfaces are > on dhcp, and I don't want to have to rewrite the fw rules each time I > get a new addr ... already have enough with dhclient-hooks for fixing > the routing tables dns-updates, etc ;-) What I basically want to do is > make the proxy's request to go out the same ifc as the masqueraded > packets getting a src addr of s41.s42.s43.s44. Other locally generated > packets should get a src addr s21.s22.s23.s24. > > To accomplish this I'm using iptables to mark all, to port 80, locally > generated tcp packets: > > % iptables -t mangle -vnL OUTPUT > Chain OUTPUT (policy ACCEPT 3234 packets, 2254K bytes) > pkts bytes target prot opt in out source destination > 1114 181K MARK tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 MARK set 0x4 > > I have verified that the iptables rule marks them fine enough. > > Then the ip rule with prio 99 below should then catch them and route > according to table eth4 below. That rule however does, for some reason > not match those packets, instead they are routed according to table > eth2 below (prio 200 rule), getting src addr s21.s22.s23.s24. If I > disable that rule they are routed according the the prio 300 rule > (getting src addr s31.s32.s33.s34). > > ... > > > What am I doing wrong here? Source address selection happens before the packet is even generated, so iptables marking in OUTPUT can't affect it. -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
