multi user vncserver

bartman
2025-10-04

Table of Contents

Let’s setup an Ubuntu 24.04 Server and give multiple users to it using VNC.

So, I have an Ubuntu 24.04 server in the lab, and I need to get multiple users to VNC in. Not my favourite way to use a UNIX system, but all the hardware tools are graphical, and this is the way design is done.

To keep things light, we will use lightdm greeter and xfce4 desktop.

I’m assuming that you know how to setup Linux user accounts, SSH server, SSH keys, and all that stuff.

Initial System Preparation #

Update system:
```
1sudo apt update
2sudo apt upgrade -y
```
Install lightweight desktop and display manager:
```
1sudo apt install xfce4 xfce4-goodies lightdm -y
```
Select lightdm during installation.

Install extra fonts:

1sudo apt install xfonts-base xfonts-75dpi xfonts-100dpi xfonts-scalable -y

Install dummy video driver:

1sudo apt install xserver-xorg-video-dummy -y

Configure /etc/X11/xorg.conf:

 1Section "Device"
 2    Identifier "Configured Video Device"
 3    Driver "dummy"
 4    VideoRam 256000
 5EndSection
 6
 7Section "Monitor"
 8    Identifier "Configured Monitor"
 9    HorizSync 5.0 - 1000.0
10    VertRefresh 5.0 - 200.0
11    Modeline "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync
12    Option "PreferredMode" "1920x1080_60.00"
13EndSection
14
15Section "Screen"
16    Identifier "Default Screen"
17    Monitor "Configured Monitor"
18    Device "Configured Video Device"
19    DefaultDepth 24
20    SubSection "Display"
21        Depth 24
22        Viewport 0 0
23        Virtual 1920 1080
24        Modes "1920x1080_60.00"
25    EndSubSection
26EndSection

Enable graphical boot:

1sudo systemctl set-default graphical.target
2sudo reboot

Disable LightDM (to avoid conflicts):
```
1sudo systemctl stop lightdm
2sudo systemctl disable lightdm
```
… this is optional, but I don’t need any local logins.

Purge GNOME/Ubuntu desktop:

1sudo apt purge gnome* ubuntu-desktop -y
2sudo apt autoremove -y

… it’s slow over VNC.

Purge Wayland packages:

1sudo apt purge wayland* libwayland* -y
2sudo apt autoremove -y

Set XFCE as default session for all future users:

1echo -e "[Desktop]\nSession=xfce.desktop" > /etc/skel/.dmrc

Set XFCE as default session (for each existing user):

1echo -e "[Desktop]\nSession=xfce.desktop" > ~/.dmrc

Disable Suspend and Power Management #

Mask suspend targets:

1sudo systemctl mask sleep.target suspend.target hibernate.target hybrid-sleep.target

Configure XFCE power manager (/etc/xdg/xfce4/xfconf/xfce-perchannel-xml/xfce4-power-manager.xml):

1<?xml version="1.0" encoding="UTF-8"?>
2
3<channel name="xfce4-power-manager" version="1.0">
4  <property name="power-manager" type="empty">
5    <property name="inactivity-on-ac" type="uint" value="0"/>
6    <property name="inactivity-sleep-mode-on-ac" type="int" value="0"/>
7  </property>
8</channel>

… without this change, XFCE would suspend the system when idle.

Disable LightDM greeter suspend (install dbus-x11 first):

1sudo apt install dbus-x11 -y
2sudo -u lightdm dbus-launch gsettings set org.gnome.settings-daemon.plugins.power sleep-inactive-ac-type 'nothing'
3sudo -u lightdm dbus-launch gsettings set org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout 0
4sudo -u lightdm dbus-launch gsettings set org.gnome.desktop.session idle-delay 0
5sudo systemctl restart lightdm

… if you disabled lightdm above you don’t need this.

Handle Notifications and Snap #

Fix xfce4-notifyd (/etc/systemd/user/xfce4-notifyd.service.d/override.conf):
```
1[Service]
2Environment="DISPLAY=:0"
```
```
1sudo systemctl daemon-reload
2sudo systemctl restart lightdm
```
… only restart if you still have lightdm enabled.
Remove snapd-desktop-integration:
```
1sudo snap remove snapd-desktop-integration
```
… optional, but it spamming my logs with messages.

TigerVNC Installation and Configuration #

Install TigerVNC:

1sudo apt install tigervnc-standalone-server tigervnc-common -y

Make VNC start xfce4 desktop for any future user:

Edit /etc/skel/.vnc/xstartup:

1#!/bin/sh
2unset SESSION_MANAGER
3unset DBUS_SESSION_BUS_ADDRESS
4exec startxfce4

then

1chmod +x /etc/skel/.vnc/xstartup

For each user:

Edit ~/.vnc/xstartup:

1#!/bin/sh
2unset SESSION_MANAGER
3unset DBUS_SESSION_BUS_ADDRESS
4exec startxfce4

then

1chmod +x ~/.vnc/xstartup

Create /etc/systemd/user/vncserver@.service:

 1[Unit]
 2Description=VNC Server for display :%i
 3After=network.target
 4
 5[Service]
 6Type=simple
 7ExecStartPre=/bin/sh -c '/usr/bin/vncserver -kill :%i > /dev/null 2>&1 || :'
 8ExecStart=/usr/bin/vncserver :%i -geometry 1920x1080 -depth 24 -localhost no -SecurityTypes Plain -pam_service login -fg
 9ExecStop=/usr/bin/vncserver -kill :%i
10Restart=always
11
12[Install]
13WantedBy=default.target

Enable linger for each user:
```
1sudo loginctl enable-linger <user>
```
(this lets systemd session live longer than the ssh login)

Now, each user will get a port to connect to and an Xserver. You will need to map these.

For example, if I have 3 users I might have:

username	X session #	TCP port
bob	1	5901
frank	2	5902
joe	3	5903

As each user, and not as root, enable and start service:

1systemctl --user daemon-reload
2systemctl --user enable vncserver@<X>
3systemctl --user start vncserver@<X>

(replace <X> with X session number of that user)

Firewall Configuration #

Allow VNC ports from VPN subnet:

1sudo ufw allow from 10.0.0.0/8 to any port 5900:5999 proto tcp
2sudo ufw reload

Connection #

From another system, connect with TigerVNC client:

1vncviewer -SecurityTypes Plain <server-ip>:590<N>

Use system username and password for authentication.

Working around snaps #

Both Firefox and Chromium in Ubuntu are usually installed with snaps. But snaps were not working, and I had disabled them above because of spamming the logs.

Snaps didn’t work for me in VNC. Here is how I installed firefox.

1sudo snap remove firefox
2sudo add-apt-repository ppa:mozillateam/ppa -y
3echo -e 'Package: *\nPin: release o=LP-PPA-mozillateam\nPin-Priority: 1001' | sudo tee /etc/apt/preferences.d/mozilla-firefox
4echo -e 'Package: firefox*\nPin: version 1:1snap*\nPin-Priority: -1' | sudo tee /etc/apt/preferences.d/mozilla-firefox-snap
5sudo apt update
6sudo apt install firefox -y

This might work for chromium. Didn’t try.

1sudo snap remove chromium
2sudo apt install apt-transport-https software-properties-common wget -y
3echo 'deb http://deb.debian.org/debian bookworm main' | sudo tee /etc/apt/sources.list.d/debian-stable.list
4echo -e 'Package: *\nPin: release a=stable\nPin-Priority: 500' | sudo tee /etc/apt/preferences.d/chromium
5echo -e 'Package: chromium*\nPin: origin deb.debian.org\nPin-Priority: 700' | sudo tee -a /etc/apt/preferences.d/chromium
6sudo apt update
7sudo apt install chromium -y

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Linux
Vnc

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