IPSEC_ESP port 50 Traffic even when IKE Phase-1 is not up

UtkarshKumar — Wed, 11 Sep 2024 21:53:54 GMT

We are running into an issue, where we have 2 Palo Firewalls and we are trying toe establish S@S VPN between them. Both the tunnels are behind NAT devices and we do have NAT-T Enabled.

We can see in IKE MGR.logs that the initiator is trying to reach out on 4500 after initial Port 500 traffic.

The issue we see is that there is "IPSEC-ESP" port 50 traffic even though the phase-1 is not coming up on Session Browser and if we try to clear the traffic the session ID changes but this traffic does not get cleared.

The issue this causes is that even if we clear VPN ike-sa and ipsec-sa tunnels from the firewall we are not seeing port 500 traffic being generated again when we try to initiate the tunnel using "test VPN" command.

The only time we are trying to generate this traffic again is by rebooting the firewall completely. We are running PanOS-11.1.4-h2 on the firewall.

Initially, we had a "Tunnel Monitoring" set. However, we cleared this, deleted the tunnel, and recreated we still see "IPSEC-ESP" port 50 traffic but no port 500 traffic was generated after a few initial packets.

Has anyone faced this issue? We do not see any timeouts or any other stating why the tunnel is not coming up.

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IPSEC_ESP port 50 Traffic even when IKE Phase-1 is not up