[c-nsp] IP NAT Traversal and PXF

Palis Michael security at cytanet.com.cy
Thu Feb 2 04:26:58 EST 2006

Hello all


We have a strange problem with customers running VPN clients with NAT
Traversal to connect to their remote networks. Problem is as follows:


We have a few C7400 andf C7304 which terminates adsl users. The routers are
doing NAT for the ADLS users. It seems that there is a problem with clients
with NAT Traversal and IP PXF configuration on Routers


Disabling IP PXF the user can pass traffic though the IP-Sec Tunnel. In case
IP PXF is enable, Tunnel can be established but no traffic can pass through.
With out NAT -Traversal on the clients VPN software , there is no problem
either with the tunnel establishment or traffic. 


I searched Cisco but I did not find anything which relates NAT Traversal and


Any suggestions or help will be appreciated!!




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