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Is this port necessary for RDP to function over a VPN?
RaHorn
Newbie ✭
I have two NSA2650s at different geographical locations connected through a VPN. When I RDP from one client to another through the VPN, I see the normal port for RDP, 3389, but it's paired with another port, 55669. Where is this second port being generated from? I've been tasked with closing\blocking all non-critical business ports. Is this port generated dynamically at one of the firewalls?
Thanks.
Category: Firewall Management and Analytics
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OptionsCORRECT ANSWERArkwright
All-Knowing Sage ✭✭✭✭
The client randomly generates the source port. The port is not "open" in any meaningful sense. It will not accept new connections from anywhere, it will only accept packets from the destination host:port.
This is not specific to RDP, this is how TCP works.
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Answers
Hi @RaHorn ,
The second port number, are you seeing this as the source or destination port in the packet conversation?
It flips. Here's a picture:
Thanks for the screenshot @RaHorn
This is the source port remap option on the NAT policy. It remaps the source port for the connection.
If you want to disable it, please see the information in the following article (It says regarding voip, but the information to disable the source port remap is in the article):
Troubleshooting a scenario where Source remap is causing the VOIP issues | SonicWall
@Arkwright ,@TonyA Thank you both for your help. Very much appreciated.
Great explanation @Arkwright Thank you !