Overview

VNCD is a daemon that automatically spawns X servers and sessions for VNC clients.

1. Each user is assigned a unique port.
2. When VNC client connects to this port a server script, specified by VNCD_SERVER environment variable, is executed. User id, group id and local port are passed via environment variables VNCD_UID, VNCD_GID and VNCD_PORT respectively.
3. After the port becomes active a session script, specified by VNCD_SESSION environment variable, is executed.

VNCD can be used with any VNC server, but we tested only TurboVNC. The advantage of using VNCD over plain VNC is that you no longer need to log in to the server via SSH to spawn personal VNC server: instead you run VNCD, connect to your unique port, type login and password (using UnixLogin authorisation method of TurboVNC) and go on with your work.

TurboVNC server and session scripts

Here is an example of server script for TurboVNC.

set -e

# log everything to home directory
log_directory=$HOME/.local/log
mkdir -p "$log_directory"
exec > "$log_directory/turbovnc.server.log" 2>&1

# generate keys
h=$(hostname)
key=/etc/opt/VirtualGL/vgl_xauth_key
xauth add "$h/unix:$VNCD_UID" . $(mcookie)
xauth merge $key

# X server
exec /opt/TurboVNC/bin/Xvnc \
	:$VNCD_UID \
	-securitytypes UnixLogin \
	-pamsession \
	-rfbport "$VNCD_PORT" \
	-fp catalogue:/etc/X11/fontpath.d \
	-once \
	-nevershared \
	-noreverse \
	-localhost

The corresponding session script is the following.

unset VNCD_ARGS
unset VNCD_SERVER
unset VNCD_SESSION

# log everything to home directory
log_directory=$HOME/.local/log
mkdir -p "$log_directory"
exec > "$log_directory/turbovnc.session.log" 2>&1

# clipboard
/opt/TurboVNC/bin/tvncconfig &

# display manager
exec vglrun -fps 60 dwm

Build and install

We use Meson build system to build and install the programme.

meson . build
cd build
ninja
ninja install

Usage

In order to run VNCD you need to specify at least access group and bind address. Each user from the access group is given a unique port calculated as base-port + user-id. Default base port is 50000.

# bind ports for all users from vnc-users group
# listen on 0.0.0.0 address
vncd -g vnc-users 0.0.0.0

To see all options use help command.

vncd -h