IPSec Pass Through on ASA

Question

I have a third party firewall behind a Cisco ASA. The Cisco ASA is doing PAT as there are no other IP addresses available. The third party firewall is attempting to build an IPSec tunnel to another firewall. The IPSec tunnel is not coming up. When I do a capture on the Cisco ASA firewall I see traffic hit the inside interface and leave the outside interface. I then see the reply traffic return and hit the outside interface of my Cisco ASA but it is not being allowed to pass through to the inside interface.I have enabled NAT-T on the thrid party firewall but it still does not get the reply traffic becuase it gets stopped at the Cisco ASA.
Any thoughts?

Answer 1

Is your third party FW attached directly to your ASA? If not, do you have a route to that device on your ASA?
Please perform a packet-tracer to see why the return traffic is not reaching the third party FW..
packet-tracer input outside udp 500 500 detail
If the packet-tracer shows traffic going through successfully, perhaps it is your third party FW that is blocking the traffic?
Please reply with packet-tracer results.
Kind Regards,
Kevin
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