IOS Firewall how to open port to server inside

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I have a CISCO 1711 Security Router (Firewall feature set) that is our connection to the Internet. I am using NAT overload (PAT) and want to open a port to a mail server on the inside. Can I do this by just adding an entry in the acl for the outside interface and then using an ip port-map smtp port 25 list xx command.



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sachinraja Mon, 11/15/2004 - 23:45
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hello gary..

you have to do a static NAT to the server before proceeding to open the ports.. on the router use the command:

ip nat inside source static ......

give the inside and the outside ip addresses... then proceed with the access-list command which will allow only port 25 access from outside...

All the best !!

tyagivijay Tue, 11/16/2004 - 00:15
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hello Gary ,

All the Ports in Cisco IOS are open by default , until & unless you have made a access-list to block certain applications.


Vijay Tyagi


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