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Community Member

Cisco 1750 and MS VPN

I'm trying to set up a MS VPN behind a Cisco 1750 router. The MS Server has a local IP of and a public address of The router is configured to NAT all traffic to When I connect from another computer inside the router (IP address, for instance) the VPN works perfectly. When attempting to connect via the internet, however, the VPN server doesn't respond. Port 1723 is detected, but no connection is made. I'm guessing that this is because the 1750 must be specifically configured to route GRE to, but I've been unable to figure out how to do that.

My router is a 1750, IOS version 12.0(5)XQ, and the ROM is bootstrap version 12.0(3)T. The router has 12Mb of RAM, and 4Mb of system flash.

I have a few questions:

1) Will I have to upgrade the IOS to get this to work? If so, what version will I need to upgrade to?(Will I need to upgrade the RAM or flash to upgrade to the proper IOS version?)

2) Should this be working, or did I miss something?

Many thanks, in advance, for any light you can shed on my problem!

Community Member

Re: Cisco 1750 and MS VPN

You can’t use GRE when running port translation. PAT only supports TCP and UDP IP Protocols. You’ll need another IP address to map that server to for access on the outside.

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