VPN through NAT?

[Troy Settle]

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,

-- 

--
  Troy Settle
  Pulaski Networks
  http://www.psknet.com
  866.477.5638