I am trying to add a linux firewall to a company’s network
Here’s my situation… Internet –> CISCO Router –> Linux Firewall –> Private LAN. On the private LAN behind the firewall, I have an exchange server. I changed the exchange server’s oldIP to a private IP. The linux box uses another public IP address.
I can browse the internet thru the proxy. I can send and receive email internally. I can send email to the outside world. But I cannot receive email from the outside world.
I use ipchains and ipmasqadm on the linux box that is supposed to forward email on port 25 to the private IP of the exchange server. It is a basic setup based on all the documentation I’ve read, but I can’t get the outside email to the exchange server. Is it possible that I need to change the linux server’s IP to the old public IP that the exchange server used to have? Since this is the IP that the ISP recognizes for email?
Thanks for any suggestions.