Globalprotect traffic translated to port 20077

[mkukucska]

Hi Team, in our test env I have a firewall with GP config. I would like to NAT the GP traffic to a loopback interface. Original destination port is 50443 and a NAT rule is set up to translate it to 443 (and the dest address as well...)

However, if I send a connection request from client it reports that the portal is unavailable. From the firewall logs it is visible the NAT in regards of the ip addresses are working well (so the trafic hits the proper rule) but somehow the destination port is turned to 20077 instead of 443, so there is no any response for the request of course. What could be the reason behind it?

Thank you in advance for any hint!

[JayGolf]

Hi @mkukucska ,

It looks like the traffic isn't hitting your DNAT rule. I see the details of the traffic log and I see source zone WAN, but a destination zone of VPN. 

[mkukucska]

Hi Jay,

As you can see the test policy match screenshot, traffic is matching the proper rule. Additionally, the destination ip address is turned to the proper one.

VPN zone is visible in the security log details, because in the case of incoming traffic the security policy, if NAT is in place, must be configured with pre-nat ip address but with post-nat zone.

Any other hint related to the issue?

Kind regards,

Mihaly

[KuehnAnd]

I have the same issue since a few days. And i didnt made any changes to the firewall. I also tried to create a no-nat Rule at the Top of the nat Policies without any effect. I also configured the gatway and portal from the loopback interface back on the external puplic ip directly and there is still a nat to  port 20077. saved a config file and looked at all nat rules. There is not nat rule that include port 20077.

[ExternalSupport]

Hi

Since I moved a vsys config from a 3260 to a 460, my dual GP portal configuration is facing the same behaviour (not sure if the migration is related).

Dnat port from 443 to 20077 without reason.
A test nat policy in CLI indicate no results but monitoring for the same request show a nat rule match.
By the way, when I check the session ID in cli, I see (vsys1) for the NAT line but no rule name associated as it should be.

It's really weird, even if GP is still working correctly.
Let me know if you find any tips on that subject.

[mkukucska]

Hi,

I opened a support ticket related to this case a few months ago and the outcome was that, port 20077 is an internally used port in palo alto device for SSL VPN traffic. The GP vpn will work this way as well, so I would say, there is no additional aciton needed on this. At least we don't have any issue with GP VPN, just keep this fact in mind if you have to analyze related logs.

[ExternalSupport]

Thank you for the feedback !