RPiVNCHowTo

How to install and configure efficient LAN-based VNC for virtual desktops on Raspberry Pi OS (RasPiOS) and any other Debian-based distro.

NOTE: VNC only works on X11-based systems. More recent Ubuntu releases, such as 22.04 and later, appear to use Wayland by default. I have not had the time to sort out how to make this project work on Wayland-based systems.

Overview

There are several different VNC servers to choose from on Linux and RasPiOS, and there are many ways to install and configure VNC. This is one of the most efficient and lightweight VNC implementations for local LAN use. I've documented it so that you can use and enjoy it as well.

Once VNC is set up according to this guide, each user can use their favorite VNC client to connect, and will log in using their own username/password, receiving their own virtual desktop. Each user can customize their virtual desktop as they desire.

This guide assumes that you're installing onto a Raspberry Pi on your local LAN running RasPiOS, and does not address any extraordinary security concerns such as firewalls, port forwarding, etc. Depending on how your RPi RasPiOS security is configured, VNC may log you directly into a desktop, or you may be prompted for credentials.

These instructions have been tested on RasPiOS Buster as well as Raspbian Stretch, and details for both Full and Lite are included. In the following notes, read "sudo Edit" as "sudo nano/vi/emacs/..." as appropriate for the editor you use.

If you find this github useful, please consider starring it to help me understand how many people are using it. Thanks!

NOTE: This can be used on other Linux distros with a recent systemd implementation, although minor adjustments may be required if the distro is not Debian-based. If you run into problems, please let me know!

There are (at least) 3 different VNC servers provided with RasPiOS. RealVNC is quite elegant, comes pre-installed on RaspiOS Full Desktop, and can be used on a LAN without a RealVNC Cloud account. Using a RealVNC Cloud account provides additional functionality. RealVNC for personal use is Free, and if you use a Cloud account there is a limit of 5 internet-connected computers.

But, Linux is all about choice, and there are at least 2 other VNC servers available on Linux. The rest of this document is about how to most effectively configure these other VNC servers.

This method only configures VNC virtual desktops. If you want to connect to the system console, you probably want to do it for the best performance. In that case, you should probably use RealVNC, which is much more optimized for that use case. And note that you can use these virtual desktops alongside RealVNC Server, and have the best of both worlds. NOTE: Only TigerVNC cooperatively coexists with RealVNC. Installing TightVNC server seems to cause RealVNC Server to be uninstalled.

TightVNC is a very nice VNC server, as well, but I found that at least one font was not always displayed correctly (9x15bold, specifically, which I have used for far too long in my xterm windows). Additionally, installing TightVNC forces the removal of realvnc-vnc-server, which is needed if you want to access the Console session in addition to virtual sessions.

The third VNC server is TigerVNC. The rest of this document is based on TigerVNC. (As an aside, TightVNC can be used with this method as well, however, the ExecStart command in the .service files that starts VNC is specific to TigerVNC and will need adjustment for tightvnc by changing Xtigervnc to Xtightvnc, in addition to installing the tightvncserver package.) NOTE:make-systemd-xvnc adjusts the command lines automatically for TightVNC.

TigerVNC (and TightVNC and RealVNC as well) provide a tool that greatly simplifies running a VNC server (/usr/bin/vncserver) with little to no config file editing. However, this method isn't optimal from a system resources perspective in that it keeps a VNC server running whether you're using it or not, and you need to either manually start it or sort out how to automaticallly start it when the system reboots. It is, however, a much simpler way to get started for some people. The method described here starts the requested VNC server on-demand, and is fully integrated into Linux systemd.

Should you use /usr/bin/vncserver or this method? If you have never typed into a terminal on Linux, vncserver was made for you. On the other hand, if you're moderately comfortable working with the Linux bash command line and are able to make simple file edits, the method documented here is a much efficient.

A Note about RealVNC and these virtual desktops

It is absolutely possible to use RealVNC server for graphical console access and virtual desktops enabled by this github on the same system. In fact, if you'd like to do this as easily as possible, I encourage to take a close look at sdm.

sdm makes it super-easy to configure RasPiOS (Desktop or Lite) with all your favorite settings, apps and configurations (my fairly fully-loaded IMG takes about 10 minutes to configure on a Pi4). Then, when you need a new SD Card, you just burn one from your customized image. The system comes up with all Localization settings in place, WiFi configured, apps installed, etc. And, one of the things that sdm will configure for you is VNC. Have a look!

But, if you'd prefer to not use sdm, that's fine. RealVNC Server (which attaches to the Pi4 graphical console) works great with TigerVNC-powered virtual desktops installed using the technique on this github. make-systemd-xvnc and this documentation skip port 5900 for RealVNC compatibility.

So, either using sdm or this technique, if you want to have RealVNC and TigerVNC-powered Virtual Desktops on the same system, it just works.

Installing onto RasPiOS Full

Full RasPiOS comes with the realvnc-vnc-server package installed. You can remove it or not. Then execute the following commands:

TigerVNC server: sudo apt-get install tigervnc-standalone-server xfonts-scalable xfonts-100dpi xfonts-75dpi --no-install-recommends
TightVNC server: sudo apt-get install tightvncserver xfonts-scalable xfonts-100dpi xfonts-75dpi --no-install-recommends

Continue by performing the following steps:

sudo edit-lightdm-config
sudo make-systemd-xvnc
sudo reboot

NOTE: DO NOT install any of the packages suggested below for RasPiOS Lite

If you are have multiple different users login to the same Pi, you'll need to disable AutoLogin in sudo raspi-config: System Options, S5(Boot/Auto Login), and then set B3 (Desktop).

Installing onto RasPiOS Lite

RasPiOS Lite is exactly that...Lite. You'll need to install a few more packages to use these dynamic virtual desktops.

Install the basic XServer software and xterm
- sudo apt-get install xserver-xorg xserver-xorg-core xserver-common xterm xfonts-base xfonts-100dpi xfonts-75dpi xfonts-scalable
TigerVNC Server: sudo apt-get install tigervnc-standalone-server
TightVNC server: sudo apt-get install tightvncserver
You'll need a Display Manager. I prefer xdm, but wdm and lightdm are good choices as well. sudo apt-get install xdm or sudo apt-get install lightdm as appropriate.
You'll also need a Window Manager. I prefer icewm, but you might | probably will prefer something different. In any case, you'll need to sudo apt-get install your Window Manager of choice.

System Configuration

This section describes in more detail the system configuration changes required to enable virtual VNC desktops. If you follow the directions for RasPiOS Full, you do not need to do any of this if you've performed the steps described above for Installing onto RasPiOS Full.

Display Manager Configuration

The most popular Display Manager on RasPiOS is lightdm, and lightdm is installed by default on RasPiOS Full. I've documented xdm as well. In either case, the Display Manager must have XDMCP enabled, so that VNC can create the desktop.

In either case, on RasPiOS Lite, after updating the display manager configuration per the following details, issue this command on the console: sudo systemctl set-default graphical.target.

Lightdm Configuration

sudoedit /etc/lightdm/lightdm.conf and modify the XDMCPServer section as follows

[XDMCPServer]
enabled=true
port=177

The edit-lightdm-config script on this github can be used to make this edit.

After you've completed this change, sudo systemctl restart lightdm.service to restart the service with the new settings (this will log out your session!), or restart your system. If you don't, you'll only see a black screen when you connect to the system with a VNC viewer.

If you prefer to not have lightdm to run on the (HDMI) console, that is, you only want a command-line console, sudoedit /etc/lightdm/lightdm.conf again and after the line #start-default-seat=true add this new line.

start-default-seat=false

xdm Configuration

xdm is a lightweight Display Manager with less capabilities than lightdm. That said, I've found it to consume less system resources than lightdm, and can be coupled with choosewm (see Appendix below).

sudo Edit /etc/X11/xdm/xdm-config and comment out the line DisplayManager.requestPort by adding a "!" at the start of the line.`
sudo Edit /etc/X11/xdm/Xaccess and uncomment the line that has #any host can get a login window by removing the '#' at the start of the line.
If you don't want a graphical login on the Raspberry Pi HDMI port sudo Edit /etc/X11/xdm/Xservers and comment out the line :0 local /usr/bin/X :0 vt7 -nolisten tcp by adding a '#' at the start of the line.
sudo systemctl restart xdm.service to restart the service with the new settings

The edit-xdm-config script (on this github) can be used to make the above modifications.

Note: If your system has both lightdm and xdm installed you can switch between the two display managers, using dpkg-reconfigure lightdm.

VNC Service configuration

NOTE If you aren't comfortable and experienced at editing system configuration files, I strongly encourage you to use the make-systemd-xvnc script on this github.

The following explanation provides background on how to edit the configuration files, but these are not exhaustive and step-by-step.

A systemd socket/service config file pair is required for each VNC port, and each port will implement a single screen resolution. You can easily create the socket/service pair files with the make-systemd-xvnc script on this github or you can create your own in /etc/systemd/system (but make-systemd-xvnc is MUCH easier).
- Edit the VNC configuration files as needed. If you used make-systemd-xvnc you should not need to modify them unless you run into a problem.
  - If you need to edit them, sudo Edit the .service files as appropriate, located in /etc/systemd/system
  - Change the resolution in xvnc1@.service as desired. I like my VNC window to be nearly full screen size on my 1900x1200 monitor, so I use 1880x1100, which is the setting in xvnc1@.service. For my 1900x1080 laptop I use 1880x960, which I've put in the file xvnc2@.service (with a corresponding xvnc2.socket file).
  - The filenames for the .socket and the .service file must match, except for the @ in the .service filename.
  - The @ in the filename is important. When a VNC connection is made, a new service is automatically started with the name similar to xvnc1@n-serveripaddr:port-remoteipaddr:port.service. the @ enables that.
sudo systemctl daemon-reload - Must be done when systemd configuration files are modified. If you use make-systemd-xvnc you are given the option of performing the reload and starting the sockets.
Start the VNC service connections. For each one you've created (e.g., xvnc1 and xvnc2 in this example), start the socket and enable it across reboots:
- sudo systemctl start xvnc1.socket - Starts the socket in the running system
- sudo systemctl enable xvnc1.socket - Sets the socket to start after the system reboots
- sudo systemctl enable --now xvnc1.socket - Starts the socket in the running system AND sets the socket to start after system reboots
Test that you can use a VNC client to connect to your server. If you get a black screen in the VNC window make sure that you have restarted the display manager, or restart the system.

If you are using make-systemd-xvnc you can easily create all the socket/service pairs. When you create them manually, if additional VNC resolutions are needed, copy the xvnc1* files to, for instance, xvnc2.socket and xvnc2@.service. Then, sudo Edit the .socket file to change the socket number (increase by 1 from the previous), and sudo Edit the .service file to change the resolution. After the files are appropriately updated, issue the above sudo systemctl daemon-reload/start/enable command sequence for the new socket.

make-systemd-xvnc looks for existing socket/service pair files, and if found will ask if you want to replace or create additional pairs. Newly-create pairs are numbered following the last xvnc socket/service pair file.

What about using this remotely? Is it secure?

The VNC protocol by itself is insecure, so you shouldn't use it over insecure networks, such as the internet, without taking precautions. With the solution documented here you need to use a VPN or similar solution (ssh, meet-in-the middle, etc) to ensure a secure connection. As an aside, presumably that RealVNC's Cloud Connections use an enhanced VNC protocol to ensure high security.

How does this work?

Once the xvnc1.socket is started, systemd listens on the specified TCP port. When a network connect lands on that port, systemd starts the service described by the .service file with the filename corresponding to the socket name. This is quite simple and elegant, and it just works.

In the event that it doesn't just work, see the next section. LOL.

Problem Solving

If things aren't working correctly, the best approach is to look at the system log (with sudo journalctl -b) and also the status of the services with sudo systemctl status xvnc*

Things that I always look at when something doesn't work correctly:

If a VNC viewer window opens but it's black, it's a display manager problem.
- Did you reboot the system before trying to connect?
- Make sure that you've configured the display manager (lightdm or xdm) correctly, especially if you edited the config files manually rather than using the scripts from this github.
If the VNC viewer cannot connect to the server it's an xvnc socket/service pair problem.
- Is systemd listening to the assigned ports? Use sudo netstat -ltpn | grep 59 to confirm that ports 5901, 5902, ... are listed. If not, there is something wrong with your xvnc socket/service pairs
- Make sure that the socket/service pairs exist and are correct, as expected

Reporting problems or difficulties

If you are unable to resolve your issue, download and run xvnc-collect from this github, and provide the output from it (/tmp/rpivnchowto-diagnostics) with your Issue that you open on this github.

systemd configuration file listings

xvnc1.socket

The .socket file describes the socket to systemd. VNC socket numbers start at 5900, but avoid using 5900 in case you ever want to use RealVNC Server. It is suggested that you maintain these in sequential order, so that a) the stream number can be inferred from the filename (e.g., xvnc1=5901, xvnc2=5902, etc), and your future sanity is not jeapordized.

[Unit]
Description=XVNC Server

[Socket]
ListenStream=5901
Accept=yes

[Install]
WantedBy=sockets.target

xvnc1@.service

[Unit]
Description=XVNC Per-Connection Daemon

[Service]
ExecStart=-/usr/bin/Xtigervnc -noreset -inetd -query 127.0.0.1 -geometry 1880x1100 -pn -once -SecurityTypes None
StandardInput=socket
StandardOutput=socket
StandardError=journal

Appendix 1 - xdm and selecting a Window Manager

xdm does not provide a built-in way (that I'm aware of) to select the Window Manager on login. The package choosewm fills the gap. Simply apt-get install choosewm to install it. Choosewm uses the system's list of Window Managers to offer you a choice when you login.

You'll need a ~/.xsession file to enable choosewm. Here's a sample:

# set wm to default window manager
# set xchoose to "/usr/bin/choosewm" or "" to not run choosewm and use default
wm="/usr/bin/icewm"
xchoose=""
# Comment out next line to not run choosewm
xchoose="/usr/bin/choosewm"
xrdb < ~/.Xdefaults
xhost +
#
# Personal customizations
#
xsetroot -solid black
#
# run choosewm (which will run the selected wm) or the default wm
#
[ -x "$xchoose" ] && exec $xchoose
[ -x "$wm" ] && exec $wm
#
# If we get here, something is wrong, so run an xterm
#
exec /usr/bin/xterm

Note that if there is only have one window manager installed, it will be run automatically after login.

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