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 Post subject: Re: RDP Session disconnects OpenVPN during login
PostPosted: 02.07.2009 12:57 
DES
DES

Joined: 30.06.2009 09:16
Posts: 5
Sadly I can't use UDP because of the firewall at work. The curious thing is that as soon as I hit 'login' in RDP, all other connections going through the tunnel also fail for 20-30 seconds. I find it hard to believe the connection is saturated.

Equally, I wonder why tunnelling RDP directly (circumventing OpenVPN) using OpenSSH client works fine, but the same thing fails with Putty?

I used a packet sniffer and it does seem that RDP packets have the 'do not fragment' flag set in the IP header...


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 Post subject: Re: RDP Session disconnects OpenVPN during login
PostPosted: 02.07.2009 13:45 
openvpn.eu Admin
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Joined: 23.01.2006 08:05
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I can't tell you were the problem is exactly. If I must guess, I would say that the TCP forwarding code in putty and/or dropbear isn't written properly. If you can't use UDP mode, try TCP mode with OpenVPN.

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 Post subject: Re: RDP Session disconnects OpenVPN during login
PostPosted: 03.07.2009 01:30 
Tripple-DES
Tripple-DES

Joined: 11.05.2009 06:10
Posts: 10
Good thread to read..
I use RDP and VPN together

Has worked fine for 2 years, no drop outs, very reliable but slow VPN client upload 8 kb/s

Check RDP and VPN different ports usually RDP 3389 and VPN 1194

Here is an extract of my server config

proto udp # UDP tends to perform better than TCP for VPN

mssfix 1400 # This setting fixed problems I was having with apps like Remote Desktop

Win XP 32 bit SP2 server Open VPN 2.0.9 GUI


1500/256 ADSL client and server


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 Post subject: Re: RDP Session disconnects OpenVPN during login
PostPosted: 20.08.2009 16:23 
DES
DES

Joined: 20.08.2009 16:13
Posts: 3
Nice thread.
I am dealing with this problem, too.

My setup is quite different: I linux (Ubuntu 9.04) box with a standard OpenVPN package running as a virtual machine under VMware Server on a Windows SBS 2003 server as host. Internet access through a DSL line with router and portforwarding to the linux box.
The linux box is doing the routing and this setup worked perfect until yesterday.

This morning a colleague put SP2 onto the SBS2003 and since then I was facing the same problem as described above: everything's fine except of RDP sessions which are crashing the openvpn session after login.

I am really mixed up as I was using OpenVPN since many years never facing such a problem ! I'm also using tcp-server with certificates so mssfix-option will not affect the current setup / does not help.

OpenVPN is version 2.1~rc11-1ubuntu3.

Any ideas ?


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 Post subject: Re: RDP Session disconnects OpenVPN during login
PostPosted: 21.08.2009 07:28 
DES
DES

Joined: 20.08.2009 16:13
Posts: 3
Really strange: although my OpenVPN session is crashing after logon to the SBS2003 via RDP an RDP session to a SBS2008 server is working perfectly !!!

Obviously the 2003 server has a different RDP implementation as the 2008 server.


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 Post subject: Re: RDP Session disconnects OpenVPN during login
PostPosted: 29.08.2009 15:32 
DES
DES

Joined: 20.08.2009 16:13
Posts: 3
Well, I did some sniffing to find what is going wrong because I asssumed a MTU problem but in fact it seems to be a TCP problem.

Anyway, here's what I could see when sniffing on the LAN interface on the OpenVPN gateway:

The RDP session between the Windows SBS 2003 Server and the OpenVPN client is starting correct and there is no packet bigger then 1388 bytes (tunnel MTU is 1464 because we have DSL internet links on both sides). After a while I can see that the Windows Server is sending TCP retransmissions although the packet was acknowledged by the client before ! It is ending up with RST packets to restart the session which seems to be crashed.

I really have no idea what can cause this behaviour. Somebody out there having similar problems ?


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 Post subject: Re: RDP Session disconnects OpenVPN during login
PostPosted: 01.12.2009 09:21 
DES
DES

Joined: 01.12.2009 08:54
Posts: 1
I have had severe problems with the ssh tunneling + openvpn setup.

On my job pc (Win XP) I have setup OpenVPN server with bridging. I can only access this machine from the outside using RDP. So when I connect, I first use RDP to the work computer to start a cygwin shell and setup a ssh connection to my home network with a reverse tunnel to the work computer's OpenVPN port.

Then I can connect just fine to the job network using openvpn through the reverse tunnel. To connect to the other machines on the job network I had to push a route, which sends traffic through the job gateway (not using the openvpn server's IP as gateway, but the job computer's default gateway). This seems to work well and I get access to other computers on the network, also on other subnets. I did setup the OpenVPN server to give out (unused) addresses on the same subnet as the work computer's NIC, hoping that the routing would work without changes on the job network side (which it did).

But using RDP through the openvpn connection is unstable. I have got it to work, but one time it has caused a BSOD on the work computer :-(. This happened right after the logon screen in the remote desktop connection.

I have also tried to test running an openvpn server on a home computer and connecting through an ssh tunnel. This time I also got a BSOD on the XP computer at home running the OpenVPN server. The error also occurred right after logging on with RDC.

So it appears that OpenVPN through SSH tunnel is a bad idea, especially if you are trying to use RDP.


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