Port forwarding smtp

kool_kid · 12-12-2007, 11:11 AM

hiya

How do i port forward for smtp of my real ip (ISP ip) to my local ip.

Example i want to port forward all the mails coming to 202.89.16.54 port 25 to my local ip 192.168.1.44:25.

acid_kewpie · 12-12-2007, 04:07 PM

this is 100% down to your router, nothing to do with linux at all, unless you're running a linux server as the ISP router, which presumably you'd have mentioned... http://portforward.com and check the details for your router.

kool_kid · 12-12-2007, 05:08 PM

yeah my ISP ip is directly connected to my Linux box so how do i do it?

SiegeX · 12-12-2007, 06:04 PM

Code:

iptables -A PREROUTING -i $WAN_IF -d 202.89.16.54 -p tcp --dport 25 -j DNAT --to-destination 192.168.1.44

If your FORWARD policy is set to DROP then you'll need this too:

Code:

iptables -A FORWARD -o $LAN_IF -p tcp --dport 25 -j ACCEPT

If the IP 202.89.16.54 is dynamic, then just remove '-d 202.89.16.54'

Dont forget to set the LAN_IF and WAN_IF variables appropriately.

kool_kid · 12-12-2007, 07:04 PM

what do you exactly mean by "drop" becuz i would like to have both way i.e 192.168.1.44 should be able to send mails using port 25 or my ISP IP and also receive it, so what do u mean by "drop" there?

What does those variables WAN_IF and LAN_IF mean, are there keywords?

SiegeX · 12-12-2007, 07:42 PM

If you are not familiar with the DROP terminology then you should really read an iptables tutorial/howto. I recommend this one: http://iptables-tutorial.frozentux.n...-tutorial.html

And im not just trying to brush you off, if you enter in iptables rules willy-nilly and don't know what they mean then you are not doing yourself any justice and you're likely to break your connection altogether and have no idea how to undo it.

kool_kid · 12-13-2007, 06:33 AM

i know one simple rule to undo settings is through service iptables restart for sure i will not be implementing this command in the Live Envirnoment untill i undestand it myself anyway thanks for the tut