VPN Tunnel and NAT exempt

Unanswered Question
Aug 16th, 2007
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Hi,


I have a VPN set between a PIX and router. One has network 10.0.0.0 behind it and another has 192.168.1.0.


Everything is working ok with the encrypting and decrypting of packets (apart from the VPN only coming up from the PIX to the router, and not the other way around, although i am setting it to bidirectional).


The new requirement is to forward all the traffic for an IP address 193.x.x.x on the router through the VPN, into the PIX and then the PIX routes it correctly.


I added 193.x.x.x to the permit command to the access-list on the router's crypto map. The traffic still doesn't go through the VPN tunnel.


Then I added it to the NAT exempt access-list. The result was that the tunnel that was fine now continuously goes up and down. I tried to do the simmetric configuration on the PIX but to no avail.


I am sorry for the lack of configuration snippets but this is more a theoretical question. Why does the tunnel go up and down just by adding a new access-list entry to the NAT exempt list. Can anyone help me?


Thanks.


Paulo

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mattiaseriksson Thu, 08/16/2007 - 01:35
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You can't just add the new network to the crypto access-list on the router, you have to add it on both sides.


The problem you see is more likely related to that change and not to the NAT change as NAT does not directly affect the tunnel.

rajbhatt Thu, 08/16/2007 - 02:41
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Hi,

To see why the tunnel goes up and down you could check with the following :


turn on syslog at debugging level on the telnet session :


logg on

logg mon 7

term mon




Also do a debug cry isakmp and debug cry ipsec to see the status of the tunnels in ASA

and debug cry engine on the router


Raj


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