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Cisco 2620 Router NAT Port 80 Problems

Posted on 2003-11-11
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275 Views
Last Modified: 2012-05-04
I want to NAT only specific ports to my pc in order to be more secure.

When I NAT one of our external IP addresses to my computer everything works fine. And when i go to Whatismyip.com i get the IP that i NAT'ed to my computer.

When I NAT only certian ports (80, 21, 25, 3389, 2114, 4099, 5190, 5000, 5001, 110). Everything works fine, i can Terminal into my pc, and view my website from home.
However when i go to whatismyip.com i get the IP of the Serial port on my router, and not the same IP as if did a Full NAT.

This wouldnt be that big of deal but I can not access my website that resides on my computer. If I do the complete NAT i can access the site. If i do the specific ports I can not access the site from my computer only pc's external, or going through our firewall.

I hope this makes sence to someone out there.

If you need any more info let me know

Thanks!
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Question by:Mohonk
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lrmoore earned 250 total points
ID: 9724887
If it works the way you want it to with a full 1-1 static nat, but not if you do port-address translation only, and your goal is simply more security, then all you really need to do is to create a good inbound-access-list and keep the 1-1 static nat.

Example:
ip access-list extended inbound
 permit tcp any any established
 permit udp any eq 53 any
 permit tcp any host 1.2.3.4 eq www
 permit tcp any host 1.2.3.4 eq smtp
 permit tcp any host 1.2.3.4 eq 3389
 permit tcp any host 1.2.3.4 eq ftp
<etc>
 deny ip any any log  <-- the 'log' keyword here makes troubleshooting easy and lets you log attempts to gain access to other ports.

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