Hello World, 

In our previous post (xRDP – xRDP shows only black screen after authentication windows – HowTo Fix !), we have explained that a same user cannot at the same time be connected locally on the Ubuntu machine and perform a remote session.  If you try to connect in such scenario, you will end up either viewing a black screen or you will be disconnected after a few seconds.   

In this post, we will provide some workarounds that can be used to prevent such situation and allow a user to login via xRDP even if the same user account is already logged on locally on the Ubuntu machine… 

Let’s demonstrate this  

Overview

xRDP is a software alternative that allow users to perform remote connections against a Linux machine.  xRDP, while providing similar functionality as Remote Desktop Services, does not behave exactly the same way as Remote Desktop Server.   For example, it’s not possible to connect via xRDP to the console session remotely (as far as we know).  The other limitation that’s generating a lot of annoyance and frustration is that a same user account cannot be logged on concurrently locally and remotely on the system.   

If a user (let’s call him Jim) is logged on locally on the Ubuntu machine where xRDP software is installed, the same user (Jim) will not be able to acquire a desktop session while performing the xRDP Session.  Jim will see only a black screen or will be disconnected after a few seconds.   This is the default behavior !  

However, there are some workarounds that can be used to prevent the black screen when logged in locally and remotely concurrently using the same user account.  We have found so far three workarounds that can be used to prevent the black screen situation.   Please note that these are only workarounds which comes with other limitations !!! 

Workaround Options

In this section, we will show you three different ways that would allow a user to perform a remote session while already logged locally on the Linux machine.  Again, please treat this information as workarounds as some limitations would still apply within your remote session…. 

Workaround 1 – Start xRDP in Debug mode  

The first option is probably the least practical !  You have to manually start the xrdp service manually in debugging mode and only a single user will be able to connect remotely. To run xrdp in debugging mode, you have to perform the following actions

If you have performed a standard xrdp installation (ubuntu xrdp package), use this information  

step 1 – stop xrdp service  (sudo systemctl stop xrdp) 

step 2 – Open a terminal console and issue the following command 

               cd /usr/sbin  
               sudo ./xrdp -ns

step 3 – Open another terminal console and issue the following command 

               cd /usr/sbin 
               sudo ./xrdp-sesman -ns

If you have performed a custom xrdp installation (compiled from sources), use this information  

step 1 – stop xrdp service  (sudo systemctl stop xrdp) 

step 2 – Open a terminal console and issue the following command 

               cd /usr/local/sbin  
               sudo ./xrdp -ns

step 3 – Open another terminal console and issue the following command 

               cd /usr/local/sbin 
               sudo ./xrdp-sesman -ns 

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Limitations

You have to start the service in a specific way and in debug mode, it seems that only a single user connection will be accepted.  This is probably not the best option to use if you want to have local and remote access concurrently from the same user account. Check the other two options as they are easy to implement….  

Workaround 2 – using dbus-launch approach 

This trick is probably a better approach because it’s simpler to implement.  You will simply need to modify your /etc/xrdp/startwm.sh file and appending a one liner that will allow you to basically acquire the desktop while performing your remote connection even if you are already logged on locally.   To implement this trick, simply open the /etc/xrdp/startwm.sh with your favorite text editor..

sudo nano /etc/xrdp/startwm.sh

At the end of the file, locate the line test -x /etc/X11/Xsession && exec /etc/X11/Xsession and just above it add the following command

export $(dbus-launch)

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Save the file and restart the xRDP service (i.e. sudo systemctl restart xrdp) 

Now, you can give it a try.  Stay logged on locally on the machine and initiate your remote session 

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As mentioned, you will be able to remote connect to your machine 

Limitations

One limitation we have noticed is that some software or program will complain if they are already in use in one of the existing session.  For example, if Firefox is open and running on the Ubuntu machine where are logged on locally and you try to start firefox in your remote session, it will not work.  You will receive a message stating that firefox is already running  

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Another limitation with this method will be present if you are using wayland display server instead of X11 Display server.  This trick will not work if you are using Wayland solution.  

A final limitation is related to login process.  The trick here allows you to launch an additional remote desktop session.  However, if you are login first through the remote connection and try to login locally, you should still encounter the infinite loop.

Workaround 3 – unsetting DBUS_SESSION_BUS_ADRESS approach

Credits :  https://catch22cats.blogspot.com/2018/05/xrdp-blank-screen-with-ubuntu-1804.html

This trick is similar to the workaround #2.  You will also need to edit and modify the /etc/xrdp/startwm.sh file and add some additional commands to be executed when the remote session will be initiated.  To implement this trick, simply open the /etc/xrdp/startwm.sh with your favorite text editor..

sudo nano /etc/xrdp/startwm.sh

At the end of the file, locate the line test -x /etc/X11/Xsession && exec /etc/X11/Xsession and just above it add the f

unset DBUS_SESSION_BUS_ADDRESS
unset XDG_RUNTIME_DIR

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Save your file and restart the xrdp service. 

Now, you can give it a try.  Stay logged on locally on the machine and initiate your remote session 

Click on Picture for better Resolution

Limitations

One limitation we have noticed is that some software or program will complain if they are already in use in one of the existing session.  For example, if Firefox is open and running on the Ubuntu machine where are logged on locally and you try to start firefox in your remote session, it will not work.  You will receive a message stating that firefox is already running  

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However, you can always kill the process through the remote session and try to start the firefox process again and this should be working…. 

A final limitation is related to login process.  The trick here allows you to launch an additional remote desktop session.  However, if you are login first through the remote connection and try to login locally, you should still encounter the infinite loop.

Final Notes

This is it for this short post !  

By default, xRDP will only allow a single session per user account.  By default, a same user account cannot be , at the same  time, logged on locally on the Linux machine and remotely.  If a user tries to remote connect to the machine, a black screen will be presented when remotely connected.  To overcome this situation, the recommended way would be to logoff from the machine (local session) and then perform the remote desktop connection. This single connection session is really causing a lot of frustrations and annoyance. 

We had to find a way to perform local and remote connections using the same account when using xRDP.  After some research, trial and error, we have a finally found some ways and workarounds that can be used which will ensure that same user account will be able to get at the same time a local connection and a remote connection.  Use this information at your own risk as we didn’t extensively tested and worked with them.  We would strongly recommend you to logoff properly from the local session before trying to perform remote login connections 

Till next time 

See ya