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PIX 515 NAT only some traffic in VPN tunnel?

Currently I have  users that connect with the Cisco VPN client to our PIX 515e. Our  corporate network is also directly connected to our partners network, sharing common address space. I want to be able allow our VPN users to connect to certain  resources on their network. Since they already have routing for our  address space, can I allow the VPN to only NAT traffic to certain  destination addresses with a local IP address on our network? That way  the partner's network does not have to change any routing since they  would see the source address as a local IP on our network.

I don't know if I worded this too confusingly, but let me know if I need to provide any more clarification.


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Cisco Employee

PIX 515 NAT only some traffic in VPN tunnel?


yes this should be no problem - you can use policy NAT for that, e.g.

access-list polnat permit ip

nat (outside) 1 access-list polnat outside

global (inside) 1

where 10.10.10.x is the vpn pool, 172.16.x.x is the partner network, and is the address you want to NAT the clients to (this can also be "interface" if you want to use the Pix's address, or it can be a range of addresses if you want to do NAT instead of PAT).

Note that if you have nat exemption configured (aka "nat 0"), then you have to make sure the traffic to be natted does not match the nat exemption (otherwise the nat exemption takes precedence over the policy nat).