I am attempting to forward port 80 and port 25 from an IPCop FW connected to Internet via the ADSL router port and my Cisco FW connected in the protected area (Green Zone) of my LAN. A similar diagram of my network is depicted in the Cisco link https://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080093f31.shtml. The only differences are the TCP-IP addresses and the Outside Cloud which is Internet in my case.
I would greatly appreciate an hint or a clue which helps me to fix this issue I have.
Data which may better help you to understand the environment, if you can assist.
Cisco PIX Firewall Version 6.3(3)
Cisco PIX Device Manager Version 3.0(1) -------> works well if directly connected to the ADSL Router and to Internet. Everything works. Good configuration available in the attachement.
IPCop 1.4.2 ------> works well if directly connected to the ADSL Router and to Internet. I can HTTP from Internet to an a Web Server directly connected to its internat Interface. I.e. 172.16.0.8.
- Cisco PIX FW alllows all services from the internal network to reach Internet, via the IPCop Green (Internal interface);
- Traffic like Facebook, Skype, etc. is allowed from/to Internet to my protected zone and vice-versa;
- Cisco internal network is 194.20.23.X is privately assigned to an other company and used by chance but without problems for years;
- Cisco external network I/F is 172.16.0.2. It connects to the internal IPCop interface 172.16.0.1 (Green);
- IPCop external network I/F is 220.127.116.11, which connects to my ADSL Router GW 18.104.22.168.
What exactly doesn't work:
My SMTP, DNS and MAIL server public address is 22.214.171.124. If you ping to this address it responds. However, if you try to telnet to port 25, it doesn't respond. So, I am almost sure there is a rule which prevents the port forwarding to my server 126.96.36.199, which Cisco NAT translates to 188.8.131.52.
A working configuration when Cisco is directly connected to Internet;
A non working configuration when Cisco is not directly connected to Internet. (File Cisco_Config_3001.txt)