NAT / PAT & Firewall rules

[fredbloggs]

bit of a newbie question, but this operates differently to what i'm used to.

It would appear that when passing traffic through the firewall it goes through the following path

• NAT:  Where it translates the connection to the internal IP address & port
• Firewall ; Where you have to allow connections to the Internal IP & Port

Is this as expected?  I'm used to it being the Firewall allows connection to the external IP and then gets passed to NAT to redirect.

I have also struggled with PAT, when using PAT what do I enable on the Firewall as the destination IP & port?  Is it the IP/Port pre-NAT or post-NAT?

I'm sure this is noted somewhere but I just can't find it written as a simple flow of how the traffic is processed and am struggling to get a working system in this way?

Thanks for any guidance.

Mark