IPTABLES ON RED HAT ES 4?

[psyche54]

---

Hello guys, I had a little problem with a linux router that im doing.. Im trying for port forwarding for my internal email server...

Here's my scenario:

Suppose my Public IP is 203.x.x.x, which is the address of my linux router.. I want to forward requests on Ports 110 and 25 on my Public IP to my internal machine which is 192.169.100.x, which is my email server...

My problem is that my linux router doesnt forward those requests to the internal email server... if you issue "nmap -sT 203.x.x.x", results shows that ports 110 and 25 are already open...

I've been googling this but it seems every solution i tried, it seems that it isn't working... I already recompiled my kernel and uses the latest kernel, but still doesn't work...

I really appreciate your help on this matter...

[CentOS]

3 possible ways... DNAT, SNAT or just simple port forwarding.

You can try this:

iptables -t nat -A PREROUTING -p tcp -d 203.x.x.x --dport 110 -j DNAT --to-destination 192.x.x.x

Or if you want full NAT:

iptables -t nat -A PREROUTING -d 203.x.x.x -j DNAT --to-destination 192.x.x.x

For SNAT, it's:

iptables -t nat -A POSTROUTING -s 192.x.x.x -j SNAT --to-destination 203.x.x.x