Inbound NAT (not PAT) on Cisco 804 dialup ISDN connection

[sheidelbach]

I have a need to simulate a customer that has a link to the internet, and that is doing NAT for some testing. I have a Cisco 804 and an ISDN dialup connection to the internet and I was at first thinking I might be able to use that, but now I'm thinking not. I would like to be able to use this to test VPN connectivity originated from at a central site to a Cisco 831 that is behind in a DMZ through a device doing NAT.

The basic topology would be {Internet}...(ISDN dialup)[Cisco 804]....[Cisco 831)....{local lan}.

I've done LOTS of NAT, but in this case:

*There would only be one IP address assigned to the WAN interface after the PPP dialup is complete

*The only address that we would be routable to from the internet would be that negotiated ISDN interface address.

So, I'm thinking I could set the 804 up to do PAT, and outbound VPNs would work, but don't really think that I could to one-2-one static NAT, so inbound traffic to the the IP address of the BRI interface being translated, then forwarded on to a device on the inside the 804 (the 831 to be exact).

Am I crazy, or is this not doable?

Thanks

[gmarogi]

I don't think this is doable since the inbound connections will need to know the IP address to be used. Since this might vary in your case everytime a dialup connection is made the clients on internet will not know this address.