VPN3000 Client through NAT/PAT Problem

From: Jason T. Rohm (jtrohm@rohmtech.com)
Date: Mon Apr 25 2005 - 12:43:34 GMT-3


I am having a weird problem that I just can't seem to wrap my brain around today.
 
I have a customer using the Cisco VPN3000 client in a conventional IPSec configuration. (Not IPSec over TCP or UDP). The endpoint is unknown, but it is not a VPN3000 concentrator. I suspect it is a PIX.
 
The customer was having problem opening multiple session from behind his router. I suspected that it was related to doing PAT, so I configured a large pool of addresses so he could do conventional NAT. This did NOT fix the problem
 
I have confirmed that this is a router configuration problem by having the customer dial out and openning multiple sessions.
 
The router in question is a Cisco831 running 12.3(8)T6, IP Plus IPSec 3DES.
 
The NAT pool was larger than the total internal systems, and was not configured with the "overload" option.
 
The first attempt to open a connection always succeeds. However, attempts to open a second or third to the same end-point (from other machines) always fail.
 
Anyone have some ideas and/or a reference URL?
 
Thanks
 
Jason



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