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BigMike
BigMike
Explorer
October 6, 2023
Question

Cannot RDP after remote server runs Forticlient VPN to connect SSL VPN

  • October 6, 2023
  • 2 replies
  • 5549 views

Hi,

  I have a remote server, and I install Forticlient VPN 7.07 on it .

  Normally, the 1st step of my work is to RDP the remote server, and run Forticlient VPN which installed on this remote server , to make a SSL-VPN connection to another server. Then do the some other operation through the RDP connection. Pls refer to the chart below.

  Everything is fine from July, and I haven't upgrade the Win10 and anything else.

  And today I find, when I connect the SSL-VPN by Forticlient VPN, my RDP connection drops asap. And I cannot RDP unless stop the Forticlent VPN.

Snipaste_2023-10-06_23-29-14.jpg

 

   I dont know what happend , and have no clue to trouble-shooting as everthing was fine since July and I did nothing on this sever.

   Can anyone give some suggesion?

   

   Thanks.

2 replies

Toshi_Esumi
SuperUser
Toshi_Esumi
SuperUser
October 6, 2023

The network topology is still not clear. Since you, or the remote server, is using SSL VPN with FortiClient VPN, there must be a FortiGate(FGT) somewhere in the diagram. Is the center box the FGT? Then is your RDP to the remote server coming through the same FGT? Or is the remote server's SSL VPN terminated at another FGT at a different location?
If the center box is the FGT, which terminates the SSL VPN from the remote server, how can you RDP in the remote server before bringing up the SSL VPN from the remote server?

 

Toshi

AEK
SuperUser
AEK
SuperUser
October 6, 2023

Hello

Looks like you have some routing change on VPN connect that affects your RDP traffic.

Try check your server's routing table before and after VPN connection. Try check which new route was inserted that may have affected your RDP traffic.

AEK
BigMike
BigMikeAuthor
Explorer
October 7, 2023

Hi, 

   I am not network expert, so I did some google, and use route print command to list the route before and after.

  Can you help to check it?

  Sorry for the system is Chinese character.

  

 

Using vpn.Snipaste_2023-10-07_10-45-20.jpg

 

before

Snipaste_2023-10-07_10-44-31.jpg

AEK
SuperUser
AEK
SuperUser
October 7, 2023

The idea is to check if the routing from the server towards your local PC is still correct after enabling VPN connection, for example the issue may be the default gateway inserted by VPN is routing the traffic from server to PC via the wrong route (VPN).

If this is the case then the solution depends on your needs, sometimes we tell VPN not to insert a default gateway, and sometimes we add a static route on the server to reach the local PC.

AEK
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