Thursday, October 14, 2021

Globalprotect intermittent routing

Good day all,

 

I have an interesting issue i have come across. We have a few remote users reporting an issue with accessing a web page. The end users connect to the VPN and access the site with no problem. After navigating on the site for a random amount of time, they receive a timeout. Upon looking at logs, they are not disconnected from the VPN and the logs show allow for the traffic. I then moved forward to a packet capture and I noticed something interesting. There were quite a few re-transmits when the web page times out. These re-transmits however are coming from the "public" IP of the web server. Then randomly, the page loads correctly and the capture shows the internal/private IP address responding. This is a full tunnel VPN. The DNS servers internally resolve to the internal IP address. These are the same DNS servers configured on the VPN virtual interface when a user connects. What would cause this routing or DNS issue?



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