The scenario is as follows. 2 network cards and 2 isps (DSL and CABLE). DSL is static IP (eth0) and eth1 is actually an internal 192.168.0.10 ip that is nat'd by an appliance (192.168.0.1) to then get out over the cable modem. I want all traffic coming in over DSL to go out over DSL and any traffic coming in to the internal ip from other lan clients to respond on the internal ip. This all works except when I try and specify that all outgoing email should use the DSL connection. The default route for the box is set to go out over the cable modem so as to take advantage of the faster connection. The reason that I want to use DSL for all outgoing email is because external mail servers (mindspring/earthlink) are rejecting receiving mail from my server because it is coming from the cable modem which is dhcp. Here is the script I run on my redhat 7.3 box at startup but also there is an iptables command that I have saved and is restored automatically that marks traffic going out over port 25 so it can be routed over DSL. Can someone help with this script and the iptables/iproute2 connection? The email is still sending over the cable modem and I can't figure out why. I have mixed two scripts together and there are probably obvious conflicts but I am trying to learn. # $IF1 is DSL (eth0) # $IF2 is internal ip that goes out over CABLE via NAT from an appliance = faster than DSL (eth1) P1_NET=65.X.X.208 P2_NET=192.168.0.0 IF1=eth0 IF2=eth1 IP1=65.X.X.210 IP2=192.168.0.10 P1=65.X.X.209 P2=192.168.0.1 ip route add $P2_NET dev $IF2 src $IP2 table CABLE ip route add default via $P2 table CABLE ip route add $P1_NET dev $IF1 src $IP1 table DSL ip route add default via $P1 table DSL ip route add $P1_NET dev $IF1 src $IP1 ip route add $P2_NET dev $IF2 src $IP2 ip route del default ip route add default via $P2 ip route add default via $P1 dev $IF1 table mail.out ip rule add from $IP2 table CABLE ip rule add from $IP1 table DSL ip rule add fwmark 1 table mail.out ip route flush cache # this cmd is actually not part of the script but was what I executed before saving the iptables configuration iptables -A PREROUTING -i eth1 -t mangle -p tcp --dport 25 -j MARK --set-mark 1 Here is the rt_tables: # # reserved values # #255 local #254 main #253 default #0 unspec # # local # #1 inr.ruhep 200 DSL 201 CABLE 202 mail.out
