Basic Help with 1720 and NAT

[mattwilson247]

I have a Cisco 1720 router and I am able to log in to it via telnet and enable the advanced features. I want to match up one of our external IP addresses to an internal IP address. I guess that I use NAT to do this but I don't know any of the commands. How would I do this? There are already a few IPs doing this (our mailserver and firewall). I didn't configure the router but I have access to it. Thanks.

-Matt

[sachinraja]

Hi Matt,

You need to take a free IP on the inside as well as the outside interface. after this, u need to do a static mapping on the router, as given below:

config)#ip nat inside source static 10.10.10.1 202.1.1.1

where 10.10.10.1 is the inside private IP and 202.1.1.1 is the ISP global IP.

I think the nat inside/outside commands will already be there on ur interfaces, since u have told that there exists a nat already for mail server.. otherwise, just add these commands:

interface ethernet0

description CONNECTED TO LAN

ip nat inside

interface serial 0/0

description CONNECTED TO INTERNET

ip nat outside.

hope this helps.. all the best.

[mattwilson247]

That helps a bit. So at the command line all I type in is:

config)#ip nat inside source static 10.10.10.1 202.1.1.1

With the IPs as my IPs of course. The ) looks out of place. Was that a mistake? Then do I have to save the configuration? What do I do if I want to delete the interface at a later time?

Thanks.

-Matt