Multihomed system troubles

rven · 01-12-2009, 03:11 PM

Hi all.
I am planning a multihomed configuration for one of my servers. The main reason is that I want to be able to send mail thru the relays of both my ISPs.
My ethX's are as follows:

LAN1: 10.0.1.10 - GW1 10.0.1.1
LAN2: 192.168.1.15 - GW2 192.168.1.1

I want to keep GW1 as my primary and use GW2 only to connect to that ISP's mail relay.
So I tried to configure the routes like this:

Code:

route add default gw 10.0.1.1
route add -host MAILRELAY2 gw 192.168.1.1

In theory this should all work unfortunately the DNS queries for hostnames seem to go where they shouldn't, and many times this results in connections to the mailservers timing out.
What am I doing wrong?

David1357 · 01-12-2009, 05:01 PM

Quote:

Originally Posted by rven

What am I doing wrong?

Try adding routes that direct DNS queries for ISP2's mail server through LAN2. For example

Code:

[machine:~]: route add -host 4.2.2.1 dev eth1
[machine:~]: route add -host 4.2.2.2 dev eth1

This assumes that each ISP uses different DNS servers.