We have several "router" machines that gather a lot of external IP addresses on the same host and redirect, NAT or proxy the traffic to the internal network. They also act as routers for the machines on the internal network. This works fine, however I am unable to make the routing table, so I can change the source address, based on the destination a machine from the internal network want to access.
Let's say I have a router, that has public addresses
P1 (220.127.116.11/24) and
P2 (18.104.22.168/24). All traffic goes through
P1, but if necessary, the host is reachable on
P2 too. This looks like this and works fine:
> ip addr ... 1: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether aa:bb:cc:dd:ee:11 brd ff:ff:ff:ff:ff:ff inet 22.214.171.124/24 brd 126.96.36.199 scope global eth1 inet 188.8.131.52/24 brd 184.108.40.206 scope global secondary eth1:p2 ...
Now I want to use
P2 as the source address, if I want to access the Google DNS service for example (
220.127.116.11). So I add a row in the routing table like:
> ip route add 18.104.22.168 via 22.214.171.124 dev eth1 src 126.96.36.199 > ip route ... default via 188.8.131.52 dev eth1 184.108.40.206/24 dev eth1 proto kernel scope link src 220.127.116.11 18.104.22.168 via 22.214.171.124 dev eth1 src 126.96.36.199 ...
But this does not work. If I ping
188.8.131.52, the host still uses
P1 as the source address, and does not use
P2 at all for outgoing connections.
Am I doing it right? I guess not...