Force mail out the right server

Posted July 30, 2004

I meant to note this down earlier, as I'm sure it will be really handy in the future some time; I should even include it in my standard firewall script.

iptables -t nat -I PREROUTING -p tcp --dport 25 -i eth0 -j DNAT --to SMTP_IP:25

This rule takes any outbound packets that are heading with a destination port of 25 (SMTP mail) and forces them through a target mail server. In Kalgoorlie, I used this so that people didn't have to change their mail client settings. People thought they were sending mail through their ISP's mail server (iiNet's for example) but it was really getting sent out Telstra's.

4 Comments so far

  1. jason on July 30th, 2004

    nice,

    [copy & paste]

    one of the more informative blogs on my list :D

  2. mlambie on July 30th, 2004

    Thanks mate! I live to give.

  3. jason on July 30th, 2004

    i hope thats not an old prison motto you picked up somewhere…

    I have been looking on ebay for one of those cool qube machines… sadly nothing as yet.

    I just want it for my coffee table, its so damn sexy :)

  4. mlambie on July 31st, 2004

    There was a RaQ 4 for sale today at Ross Auctions, see the article I’m about to write above this one…