Help for Using VNC
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Virtual Network Computing (VNC) is a Linux remote desktop.

You need an ENCS account so that you can log in to
computation.encs.concordia.ca

You will need to (a) use a Putty terminal to start a vnc server, (b),
use a second putty terminal to make a tunnel, then (c) run a VNC viewer
on your local machine. Doing this with Linux or OSX is described
later.

For Windows, get Putty and VNC Viewer from

https://www.putty.org/
https://www.realvnc.com/

The viewer is vnc-4.1.3.exe (32 bit) or VNC64.exe (64 bit).

Side note: it can be useful to transfer files back and forth between
ENCS and your PC. This can be done with drag and drop, using WinSCP at

https://sourceforge.net/projects/winscp/

********************************************
**** VNC server, runs on ENCS machine ******
********************************************

Step 1: Use a command-line terminal (Linux or OSX) or a Putty terminal
(Windows) to log in to computation.encs.concordia.ca. It will redirect
you to one of many possible machines; the least busy one. In this
case let's assume you get sent to poise.encs.

Step 2: Start the VNC server. On the poise.encs command line, type

vncserver

The vncserver will say something like this:
New 'poise.encs.concordia.ca:2 ' desktop is poise.encs.concordia.ca:2

That "2" and "poise" is **very important** information.

The "poise" machine is running the server. The "2" means that you've
been given port 5902. It could be any number. VNC works on ports 5901,
5902, 5903,... and up.  When there are several users, the server picks
the next available port.

There are sometimes useful messages in the log file
.vnc/poise.encs.concordia.ca:2.log.

Step 3: VNC will ask you to make up a VNC password; this is different
from the login password.

You can use vncpasswd to reset the password. Or, rm ~/.vnc/passwd.

Step 4: When you're finished working, kill the vncserver.

vncserver -kill :2
You can restart it on 5902 with
vncserver :2

Important: be considerate and kill your server when you are done, so
that other people can use the port.

********************************************
*** VNC tunnel for Windows local machine ***
********************************************

Step 1: Start a second Putty terminal. We will use it to make a
tunnel. Go to 'Configuration-> Session' and for Hostname put:

myusername@computation.encs.concordia.ca ssh port 22

Step 2: In Putty 'Configuration-> Connection-> SSH Tunnels' set up port
forwarding

Source port=5902
Destination=poise.encs.concordia.ca:5902
Press Add. In the Forwarded Ports box you should now see:

L5902  poise.encs.concordia.ca:5902

Step 3: Press Open to start the terminal.

Note 1: For the destination, never put a user name, e.g. myusername@poise
Note 2: In this example the VNC server is running on poise.encs, so the
        tunnel destination should be poise.encs.concordia.ca:5902
Note 3: Do not use computation.encs.concordia.ca:5902 for the tunnel
        destination. Tunneling will fail if the second terminal's login
        gets redirected to something other than poise.

Summary:
The purpose of the 1st terminal is to start the VNC server.
The purpose of the 2nd terminal is to provide tunneling to the server.

********************************************
**** VNC viewer, Windows local machine *****
********************************************

Step 1: Run the VNC Viewer executable file vnc-4.1.3.exe (32 bit) or
VNC64.exe (64 bit) on your PC.  Ask for a connection to

localhost::5902

and give your VNC password.

Step 2: At the end of your work, kill the VNC server. First, close the
running applications. Then press the red "X" in the upper right corner
of the frame, or press F8. Then, use the Putty terminal to kill the
vncserver 5902 with

vncserver -kill :2

Important: be considerate and kill your server when you are done, so
that other people can use the port.

********************************************
**** VNC tunnel, Linux local machine *******
********************************************

Open a tunnel from port 5902 on your local machine (localhost) to port
5902 on the remote machine poise.encs.concordia.ca In an xterminal,
type

me@local_machine/>  ssh me@poise.encs.concordia.ca -f -N -C \
-L 5902:poise.encs.concordia.ca:5902

********************************************
**** VNC viewer, Linux local machine *******
********************************************

You might have /usr/bin/vncviewer. If not, then install it.  More
recently (2014) there is /usr/bin/vinagre. To run the vncviewer,
on the local machine type (note that 5902 = 2)

me@local_machine/>  vncviewer localhost:2

With a gnome desktop, you might find the vncviewer or vinagre at

Applications ->Internet ->Remote Desktop Connection
--or maybe--
Applications -> Accessories -> VNC Viewer

and in this example, use the address/port localhost::5902

Important: be considerate and kill your server when you are done, so
that other people can use the port.

********************************************
*** Tunnel and VNC viewer, Macintosh OSX ***
********************************************

Open a tunnel from port 5902 on your local machine (localhost) to port
5902 on the remote machine poise.encs.concordia.ca In an xterminal,
type

ssh -p 22 myusername@poise.encs.concordia.ca \
    -L 5902:poise.encs.concordia.ca:5902

then use the Real VNC viewer for mac and enter localhost::5902

********************************************
**** VNC Hints *****************************
********************************************

**** Favorite port?

When starting the VNC server you can use

vncserver :8

to get port 5908. It it is busy, the request will be denied. You can
always see who is on what port by typing

ps aux | grep vnc

**** Screen size

Right-click on your local machine's desktop and find out the
resolution.  Suppose it says something like 1366x768; typical for a
laptop. You can then use

vncstart :8 -geometry 1300x700

to pretty much fill up the screen. It is highly advisible to undersize
by a little bit.

**** Screen saver

You will get asked for your password after 10 minutes of idle
time. You can stop this by disabling the screensaver in
System->Preferences->Screensaver

You can speed up the VNC response by using a solid color desktop
instead of a picture. Change it with a right-click on the remote
desktop background.


**** VNC crash

If the vncviewer or server crashes (this is rare) you will have to
delete some of your files in /tmp. For example, with VNC port 5902
use
rm -f /tmp/.X2-lock; rm -f /tmp/.X11-unix/X2

In your own .vnc/ directory delete the file
.vnc/poise.encs.concordia.ca:2.pid

After a crash there might be processes hanging around, called bonobo,
gam_server, gnome-panel, gconfd. Find them and kill them, e.g. use:

pkill -9 -u $USER bonobo-activation-server
pkill -9 -u $USER gam_server
pkill -9 -u $USER gnome-panel
pkill -9 -u $USER gconfd

<!-- **** VNC is slow?

On rare occasions and for unknown reasons, the vncviewer might become
super-slow.  I suspect that running vncviewer and xming (an x-server)
at the same time can cause hangups. So don't run xming. Another thing
to try is quit and restart vncviewer. -->

********************************************
****** Using the Right Window Manager ******
********************************************

If the remote desktop shows no usable functions, e.g. a terminal, you
probably have a problem with the window manager startup file .vnc/xstartup
The following works for me in ENCS; it uses the Motif window manager mwm.

File .vnc/xstartup contains:
#!/bin/sh

# Uncomment the following two lines for normal desktop:
#unset SESSION_MANAGER
#exec /etc/X11/xinit/xinitrc

xterm -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
mwm &  #using the motif window manager
#

You should also copy the mwm config file:
cd; cp /etc/X11/system.mwmrc .mwmrc; chmod 644 .mwmrc

If you are reading this, then VNC is not working and you have no access
to a GUI. There are two solutions:

(a) copy my xstartup and make it executable:

cd ; cp ~paknys/xstartup   ./.vnc ; chmod 755  ./.vnc/xstartup

or

(b) logged in with Putty, type it in using an editor such as pico that
does not require a GUI.

cd
pico .vnc/xstartup
Type the file, save it, exit the editor
chmod 755 .vnc/xstartup

********************************************
**** Make it Automatic *********************
********************************************

You can simplify your life by using scripts. On my machine I keep them
in /usr/local/bin and are shown below. You are free to copy them. I do
not offer any guarantees or addtional help for this topic.

vncstart   ;start the server
vncstop    ;stop it
vncclean   ;clean up files, if it crashed

Typing the command with no arguments prints out help.

****/usr/local/bin> cat vncstart

#!/bin/tcsh
# RP March 9, 2012
# For port 5902, usage: vncstart 2
if($#argv  == 0) then
echo 'Usage:'
echo 'vncstart 2 4x3    =>port 5902, size 4x3 on 1280x1024'
echo 'vncstart 2        =>port 5902, with default 4x3'
echo 'The size options are: 4x3 or 16x9 or lowres'
echo '------ Server not started. ------'
endif
#
if($#argv  == 1) then
echo 'Assuming 4x3 on 1280x1024'
vncserver :$1 -geometry 1270x950 -depth 16
endif
#
if($#argv  == 2) then
if($2 == "4x3")then
echo 'Assuming 4x3 on 1280x1024'
vncserver :$1 -geometry 1270x950 -depth 16
endif
if($2 == "16x9")then
echo 'Assuming 16x9 on 1680x1050'
vncserver :$1 -geometry 1670x970 -depth 16
endif
if($2 == "lowres")then
echo 'Assuming low resolution 4x3 on 1024x768'  #classroom 4x3
vncserver :$1 -geometry 1000x700  -depth 16
endif
endif
#
if($#argv  >0) then
cat $HOME/.vnc/$HOSTNAME\:$1.log | grep -s Listening\ for\ VNC
endif
#

**** /usr/local/bin>cat vncstop

#!/bin/tcsh
# RP March 9, 2012
if($#argv  == 0) then
echo 'Usage:'
echo 'vncstop 2      =>Stop the VNC server on port 5902'
echo '------ Nothing done. ------'
endif
if($#argv  == 1) then
vncserver -kill :$1
endif
#

**** /usr/local/bin>cat vncclean

#!/bin/tcsh
# RP March 9, 2012, rev. March 9, 2013.
# Usage vncclean 2
if($#argv  == 0) then
echo 'Usage:'
echo 'vncclean 2   =>remove bad files from server crash, for port 5902'
echo '------ Nothing done. ------'
endif
#
if($#argv  == 1) then
echo 'Removing:   /tmp/.X*-lock and /tmp/.X11-unix/X*'
/bin/rm -f /tmp/.X$1-lock; /bin/rm -f /tmp/.X11-unix/X$1
echo 'Removing:  '.vnc/  .pid file'
/bin/rm -f $HOME/.vnc/$HOSTNAME\:$1.pid
echo 'If present, kill bonobo, gam_server, gnome-panel, gconfd '
pkill -9 -u $USER bonobo-activation-server
pkill -9 -u $USER gam_server
pkill -9 -u $USER gnome-panel
pkill -9 -u $USER gconfd
endif
#

Last update May 14, 2020 by R. Paknys
</PRE>