Remote Desktop/GUI Access to Whistler

Configure VNC (Only need to do this one time)

TigerVNC, which is a VNC server program, has been installed on Whistler. All we need to do is to modify ~/.vnc/xstartup.

First, if ~/.vnc/xstartup already exists, back it up by moving it:

mv ~/.vnc/xstartup ~/.vnc/xstartup.bak

If it does not exist, create it and set its permission:

cd ~
mkdir .vnc
cd .vnc
touch xstartup
chmod 700 xstartup

Then add the following lines to it (via nano or vim):

#!/bin/sh
unset SESSION_MANAGER
unset DBUS_SESSION_BUS_ADDRESS
startxfce4 &

[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
xsetroot -solid grey
vncconfig -iconic &

This tells the VNC server to use xfce as its desktop (GUI) provider as opposed to the default gnome desktop. This is because gnome desktop does not seem to support multiple simoutaneous VNC sessions for one user; it also occasionally freezes and becomes non-responding.

Start VNC session

Each time you need to access remote desktop, you need to start a VNC session first via:

vncserver

(The first time you run this, it will ask you to set a password for VNC. Just set the password and remember it. If you need to change the password later, use vncpasswd.)

This will output something like this:

Warning: sled-whistler.eecs.umich.edu:1 is taken because of /tmp/.X1-lock
Remove this file if there is no X server sled-whistler.eecs.umich.edu:1

New 'sled-whistler.eecs.umich.edu:2 (<uniqname>)' desktop at :2 on machine sled-whistler.eecs.umich.edu

Starting applications specified in /home/<uniqname>/.vnc/xstartup
Log file is /home/<uniqname>/.vnc/sled-whistler.eecs.umich.edu:2.log

Use xtigervncviewer -SecurityTypes VncAuth -passwd /home/<uniqname>/.vnc/passwd :2 to connect to the VNC server.

Note the :2 above - it starts from :2 because :1 has been taken. This means this new VNC session was started at 5902 port. VNC uses ports starting from 5901. So :1 will spawn at 5901; :2 will spawn at 5902 and so on.

Now the VNC server is up and running!

Connect to a VNC session

First, we need to establish an SSH tunneling to forward the 5902 port to our own computer and then connect via localhost. To establish the SSH tunnel (on Campus Wi-Fi or UMich VPN), on your laptop:

ssh -L 59000:localhost:5902 -C -N -l <uniqname> sled-whistler.eecs.umich.edu

The command will hang there and keep running - this is fine.

Or off-VPN through jump machine:

ssh -J <uniqname>@login.itd.umich.edu  -L 59000:localhost:5902 -C -N -l <uniqname> sled-whistler.eecs.umich.edu

Then, on your laptop, open your favorite VNC client. For macOS users, the Finder already has a built-in VNC tool: Go > Connect to Server. (Btw, I recommend checkout RealVNC client for Mac users - it seems to be faster.)

To connect:

• Host: localhost
• Port: 59000

For macOS for example, enter vnc://localhost:59000 and hit ‘Connect’.

You will be asked to enter the password you set for VNC.

Then you should be entering the desktop (GUI).

Kill a VNC session

To show active VNC sessions:

vncserver -list

Look up the session number you want to terminate, e.g. :3.

To end a VNC session (e.g. :3), on Whistler:

vncserver -kill :3