VNC

VNC (Virtual Network Computing) is a remote display protocol that lets you view and interact with a graphical desktop over a network connection. In the ADL context, VNC runs a desktop session inside your proot Linux distribution and streams it to a VNC viewer app on Android.

ℹ️Termux:X11 is the preferred display method

For local use on the same device, Termux:X11 provides significantly better performance than VNC — lower latency, no compression artifacts, and native Android input handling. Use VNC when Termux:X11 is not available, when you need remote access from another device, or when running on older hardware that has compatibility issues with Termux:X11.

When to use VNC

🤔Should I use VNC or Termux:X11?

VNC is the right choice when you need to access your desktop from another device, cannot run the Termux:X11 app, have an older Android version with Termux:X11 compatibility issues, or want a headless server with occasional graphical access.

How VNC works in ADL

The VNC server runs inside your proot distribution, renders the desktop to a virtual framebuffer, and streams the pixels to a VNC viewer app. The viewer sends your inputs back to the server. Everything happens over localhost, so no network traffic leaves your device when running locally.

Installing TigerVNC

ADL uses TigerVNC, the most widely used VNC server on Linux. Install it inside your Ubuntu distribution:

$proot-distro login ubuntu -- apt update && proot-distro login ubuntu -- apt install -y tigervnc-standalone-server

Or, if you are already logged into the distribution:

$apt update && apt install -y tigervnc-standalone-server

🎯Expected Result

APT downloads and installs TigerVNC and its dependencies. When finished, the vncserver command becomes available.

Initial configuration

Setting a VNC password

The first time you start the VNC server, set a password:

$vncpasswd

🎯Expected Result

You are prompted to enter and confirm a password (minimum 6 characters). You are also asked whether to set a view-only password — enter n unless you specifically want one.

⚠️VNC passwords are weakly encrypted

VNC password storage uses legacy DES encryption. For local-only use (localhost connections on the same device) this is acceptable, but never expose a VNC server to the open internet without additional security layers like SSH tunneling.

Configuring the xstartup file

The ~/.vnc/xstartup file tells the VNC server which desktop environment to launch. Create or edit it:

~/.vnc/xstartup

#!/bin/bash
unset SESSION_MANAGER
unset DBUS_SESSION_BUS_ADDRESS
export PULSE_SERVER=tcp:127.0.0.1:4713
exec startxfce4

Make it executable:

$chmod +x ~/.vnc/xstartup

✅💡 Tip

Replace startxfce4 with the launch command for your desktop environment if you are not using XFCE. For example, use mate-session for MATE or startlxde for LXDE.

Starting and stopping the VNC server

Starting the server

$vncserver :1 -geometry 1920x1080 -depth 24

🎯Expected Result

Output similar to: New Xtigervnc server 'localhost:1' started. The :1 means the server is listening on display 1, which corresponds to port 5901.

Common vncserver flags

Flag	Purpose	Example
:N	Display number (port = 5900 + N)	:1 (port 5901)
-geometry WxH	Screen resolution	-geometry 1920x1080
-depth D	Color depth in bits	-depth 24 (true color)
-localhost yes	Only accept local connections	-localhost yes
-SecurityTypes	Authentication type	-SecurityTypes VncAuth

⭐Best Practice

Match the -geometry value to your actual screen or window size. Oversized resolutions waste processing power on scaling; undersized ones leave you with a small, cramped desktop. For a phone screen, 1280x720 or 1600x900 work well. For Samsung DeX on an external monitor, use the monitor's native resolution.

Stopping the server

$vncserver -kill :1

To stop all running VNC servers:

$vncserver -kill :*

Listing active sessions

$vncserver -list

🎯Expected Result

A table showing each running VNC session with its display number, PID, and the port it is listening on.

VNC viewer apps for Android

You need a VNC viewer app on Android to connect to the server. Here are the main options:

App	Cost	Notes
AVNC	Free, open source	Recommended. Available on F-Droid. Best touch controls, good performance.
bVNC	Free, open source	Solid alternative. Also on F-Droid.
RealVNC Viewer	Free (basic)	Available on Play Store. Proprietary but polished.

⭐Best Practice

Install AVNC from F-Droid. It is open source, actively maintained, has excellent touch gesture support, and integrates well with the ADL workflow.

Connecting the viewer

1. Start your VNC server inside the distribution (see above).
2. Open your VNC viewer app on Android.
3. Create a new connection with these settings:
   • Address: 127.0.0.1 or localhost
   • Port: 5901 (or 5900 + your display number)
4. Enter the VNC password you set earlier.
5. You should see your Linux desktop.

✅💡 Tip

If the viewer asks about encoding, choose Tight encoding for the best balance of quality and performance over a local connection.

Setting resolution and color depth

You can change the resolution without restarting the server by editing the VNC configuration, but the simplest approach is to stop and restart with new parameters:

$vncserver -kill :1 && vncserver :1 -geometry 1280x720 -depth 24

🟡Performance — Medium Impact

Higher resolutions require more processing power and memory. If you experience lag, reduce the resolution (try 1280x720) or lower the color depth from 24 to 16 bits. For Samsung DeX on an external monitor, match the monitor's native resolution.

Autostarting the VNC server

To start VNC automatically when you log into the distribution, add a check to ~/.bashrc inside Ubuntu that starts the server only if it is not already running:

$echo 'vncserver -list 2>/dev/null | grep -q ":1" || vncserver :1 -geometry 1920x1080 -depth 24' >> ~/.bashrc

⚠️Only autostart when appropriate

Autostarting VNC means every login launches a graphical session, which uses memory and CPU. If you sometimes log in just to run terminal commands, consider starting VNC manually instead.

Performance: VNC vs Termux:X11

Aspect	VNC	Termux:X11
Latency	Noticeable (compression/decompression)	Near-native
Image quality	Compression artifacts possible	Pixel-perfect
CPU usage	Higher (encoding frames)	Lower
Input handling	Translated through viewer	Native Android input
Remote access	Yes (any VNC client)	No (local only)
Setup complexity	Moderate	Simple

For day-to-day desktop use on the same device, Termux:X11 is the clear winner. VNC adds value when you need remote access or as a reliable fallback.

See Termux:X11 for setup instructions on the recommended display method, and What is Wayland? for background on display protocols.

Troubleshooting

🔧Troubleshooting

Black screen or gray screen with no desktop

Your xstartup file is either missing, not executable, or points to a desktop environment that is not installed. Verify that ~/.vnc/xstartup exists, has execute permission (chmod +x), and that the desktop environment command (e.g., startxfce4) is installed and works.

"A VNC server is already running as :1" error

A previous session was not properly shut down. Kill it with: vncserver -kill :1. If that fails, remove stale lock files: rm -f /tmp/.X1-lock /tmp/.X11-unix/X1

Connection refused when connecting from the viewer

Verify the server is running with vncserver -list. Check that you are connecting to the right port (5900 + display number). Ensure the viewer is set to 127.0.0.1, not an external IP.

Very laggy or slow display

Lower the resolution (try 1280x720), reduce color depth to 16 bits, and select Tight encoding in your VNC viewer. Close unused applications in the desktop session. Check that no other heavy processes are running in Termux or Android.

Clipboard sharing does not work

Install tigervnc-common and add vncconfig -nowin & to your xstartup file before the desktop environment command.

No audio in VNC sessions

VNC does not carry audio. Audio in ADL comes through PulseAudio over TCP independently. Ensure PULSE_SERVER=tcp:127.0.0.1:4713 is set in your environment.

FAQ

❓Frequently Asked Questions

Can I use VNC and Termux:X11 at the same time?

Not for the same desktop session. Each session is bound to one display. However, you could run two separate sessions — one on a VNC display (:1) and one on Termux:X11 (:0) — if you have enough memory. This is an advanced setup and not recommended for most users.

Is VNC secure for use over the internet?

The basic VNC protocol is not secure for internet use. The password is weakly encrypted and the session data is not encrypted in transit. If you need remote access over the internet, tunnel VNC through SSH. For local use on the same device (connecting to 127.0.0.1), security is not a concern.

What is the difference between TigerVNC and other VNC servers?

TigerVNC is a high-performance, actively maintained fork of the original VNC project. Alternatives like TightVNC and x11vnc exist, but TigerVNC offers the best combination of performance, features, and compatibility for the ADL use case.

Does VNC support hardware acceleration?

No. VNC renders everything in software, so GPU-accelerated applications will fall back to slow software rendering. For most desktop productivity tasks this is not an issue.