VPN through NAT?

[Jeff at NorrisTechs]

hmm,

I assume you have TCP port 1723 forwarding from the internet/dmz to the 
PPTP host?.  That should be enough for most PPTP based VPN clients.

It's can be difficult with IPSEC as you have to forward UDP 500, 
Protocol 50 and Protocol 51 to / from the VPN client from your NAT router.



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*/Jeff Norris/*
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Troy Settle wrote:
> Probably not the best list to ask this on, but it's the closest that 
> I'm subscribed to...
>
> I have several customers who use VPN (Windows PPTP) to connect to 
> their Corporate networks.  The first was sitting behind NAT on a 
> FreeBSD router.  The PPTP did not work.  I moved them out of NAT and 
> onto a regular IP, and it worked fine.  I then swapped out the FreeBSD 
> box with a Cisco 2620 and again tried the PPTP via NAT, but still it 
> wouldn't work.
>
> Another customer is behind a Cisco 804 and his PPTP also did not work 
> when his network was behind NAT, so I have to assign a static subnet 
> for him.
>
> From home, sitting behind NAT on my Netgear router, I can turn up PPTP 
> connections all day long.  What gives with FreeBSD and Cisco's 
> implementation of NAT that PPTP doesn't want to work?
>
> Thanks,
>