Azure VM-300 IPSec VPN Tunnels and NAT-T

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L1 Bithead

Azure VM-300 IPSec VPN Tunnels and NAT-T

Hello,

 

We have been building out several IPSec L2L VPN tunnels from Azure instance to several of our branch offices and have come across an interesting issue with a few of the newly created tunnels. The issue we are seeing is that the tunnel sessions are being created properly using IKE, but when phase 2 begins the firewall is establishing the IPSec sa's over both IPSec-ESP as well as UDP 4500. We have NAT-T disabled on both the Palo Alto VM and the remote Cisco/Juniper edge routers. The remote end is only creating the SA over ESP and not over UDP 4500. I have attempted to clear the sessions from the Palo Alto, but it continues to attempt this connection even though NAT-T is disabled. This issue only seems to occur with newly created tunnels.

 

We are running PANOS 9.1.2

 

Please let me know if anyone has seen such behaviour or if there is something that can be done to completely disable NAT-T on the tunnels.

 

Thanks in avance

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