AnsweredAssumed Answered

NAT thru VPN IPsec

Question asked by Thomas B on Nov 13, 2018
Latest reply on Nov 13, 2018 by Danny Jung

Hi all,


I come back with my NAT story...


I have a problem.


Please watch the diagram attached.



My site (green) is connected to my customer (violet) thru a VPN IPsec.

My Encryption Domain is my public range ( and the remote Encryption Domain is

My Peer is and the remote peer is


VPN are mounted between a CheckPoint and an ASA Cisco 5555.


The CheckPoint is carrying the virtual IP ( for the NAT of SRV001 with an ARP Proxy.


My customer thru the VPN has to communicate with SRV001 via the NATed IP

Then the check has to NAT it to


On the other sense, SRV001 has to communicate with SRV_CUSTOMERS (,

When SRV001 initiate the communication, the CheckPoint has to NAT is IP from to and then to send it thru the VPN.

On the other case SRV001 no need to be NATed for corporate communication.


Right now, my VPN Tunnel is UP.

When I am pinging the or with the CheckPoint it's working going thru the VPN Tunnel.

When I am pinging the or from SRV001, I saw with TCPDUMP that the firwall on the customer interface make the NAT and replace the with the but the trafic is not going thru the VPN.


How to force to send the NATed packet thru the VPN?

Support NAT-Traversal is enabled.

I saw the option in the VPN Communities the option "Disable NAT inside the VPN communitie", what is it doing?