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ScottAdair
Asked: 2011-09-24 09:45:02 +0800 CST

Cisco NAT - Sharing single public IP with multiple services

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We have this setup on a SonicWall firewall, but I can't for the life of me figure out how to do it on a new Cisco 5520. Here is what I want to do

External_IP1:25   -->   InternalMailGW_IP:25
External_IP1:80   -->   InternalWeb_IP:80

The ACLs are fine, it's just the NATing that I can't figure out.

Is there anyway to do this? I know it's probably not advised, but we have a limited number of external IPs and I don't want to go through the hassle of requesting more at this time.

firewall cisco nat ios

1 Answers

  1. Best Answer

    Assuming that the external IP is the primary IP for the interface (change that if it's not true):

    static (inside,outside) tcp interface 80 web-server-ip 80 netmask 255.255.255.255 tcp 0 0
static (inside,outside) tcp interface 25 mail-server-ip 25 netmask 255.255.255.255 tcp 0 0

    And make sure that those ports are allowed bound for the interface address on the outside interface's inbound ACL.

    Maybe look at upgrading, at least to the newest minor version of 8.2; 8.2.1 is pretty ancient. Once you hit 8.3 the config changes around a lot, but it'll convert your existing config pretty well when you upgrade.

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