SNAT not working

Chris_Unknown · 01-21-2015, 02:42 AM

Hi everyone!

I have a very strange problem that I'm currently working on.
Let me explain the situation to you:

Network diagram:

External PC -> IP: 82.12.5.1 -> Eth0
Debian Apache Server -> 192.168.5.147 -> Eth1
Internal PC -> 10.10.5.10 -> Eth2

They are all separated through a Linux Firewall (Debian 5).

Debian Apache
-
-
-
eth1
External PC ------ eth0 --- Debian FW --- eth2 -------- Internal PC

I want to setup up SNAT in the way that the Internal PC is sending packets with the source IP of eth1 (192.168.5.1).

Following rules are applied:

iptables input, forward and output are all open (default ACCEPT)

SNAT Rule:

iptables -t nat -A POSTROUTING -s 10.10.5.10 -j SNAT --to-source 192.168.5.1
iptables-save

Basically this should work right?

If not -> What am I doing wrong?

Christian

Chris_Unknown · 01-21-2015, 07:14 AM

Nobody?

Chris_Unknown · 01-21-2015, 12:22 PM

ok i solved it - but to be honest -> Have no idea why it is working now!
I changed the host IP address that should be NAT to the complete scope.
Don't know why it is working now!
Any Explanation?

Further comments: I changed the communication path from the external pc to the Apache webserver instead from the internal one to the webserver --- could this make any difference?