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Webcast-Catalyst9k
New Member

Possible to get outside address mapped to local

Is it possible to map an outside address to a server that is inside a network and connected through another router? Here is the layout

Main router 10.2.1.x

cisco switch 10.2.1.x

next router connected to switch 10.16.1.x

Can I map a static outside ip to a server on the 10.16.1.x network?

5 REPLIES

Re: Possible to get outside address mapped to local

I think you are trying to access a server from internet using a public IP when, the server is actually having a private ip from 10.16.1.x network.

Yes, you can do it.

ip nat inside source static 10.16.1.x y.y.y.y

This will create a permanent mapping on the NAT table. All outgoing connections from the server, will be NATed using ip add y.y.y.y which is a global address. If somebody tries to connect from outside....thats from the internet.... they will try using ip add y.y.y.y, and this command will translate the destination address of those connection packets, back to 10.16.1.x and hence you can access the server from internet using public IP y.y.y.y

You should have a route to 10.16.1.x in the NAT router.

New Member

Re: Possible to get outside address mapped to local

Do you know what ports need to be opened to allow instant messaging file transfers from that address? Even with the NAT static route I can't do it.

Re: Possible to get outside address mapped to local

TCP por 5190 is the port used in AOL IMs. I dont know what IM software you are using. If you dont specify port information while specify the ip nat inside source static command, all ports are opened by default.

New Member

Re: Possible to get outside address mapped to local

Here is the entry I put for my personal workstation and I am unable to transfer anything through IM of any kind.

ip nat inside source static 10.2.1.252 xx.xxx.xxx.xxx

New Member

Re: Possible to get outside address mapped to local

The AOL IM client cannot make links for transfering files and pictures through a firewall because they use embedded IP addresses that do not get NAT'ed. When you try to make a link to someone, your workstations passes your hard IP address to AOL in the payload of an IM packet, then AOL gives your hard IP address to the other IM client for them to establish a connection to you, but they usually cannot route to that address.

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