Vnc on Michael’s Domain

Remote desktop sessions to your Helsinki University work computer

Mon, 15 Jan 2018 00:00:00 +0000

If you have a work laptop, you can take it home to do work. But what if you have a desktop computer and need to access it from home? The technology to make this possible exists for more than 20 years, but if you think that University IT has made this easy for you, you would be wrong. In fact, I don’t know anybody who knows how to do this (let alone how to make the process easy). Even with the setup explained below, some things do not work well (e.g. I never could figure out how to get the file sharing to work with a Mac-to-Mac connection and thus I still use Fugu with a separate tunnelled sftp connection to transfer files). You have several options:

Startup script for VNC server

Sat, 26 May 2007 00:00:00 +0000

To start up the VNC server automatically as a service during booting, you need this shell script . You probably also can write a much simpler shell script yourself, that does the same job. In fact you will have to as this script is broken on RedHat 9. The simplest shell script is of course the command “vncserver” alone… This script goes into the folder /etc/init.d. Then you make a symbolic link in the directory /etc/rc5.d that points to the script. The /etc/rc5.d directory contains a bunch of links to scripts in the init.d file which are executed when the system is entering runlevel 5 (runlevel 5 is the one where you have the gui and multiple users enabled, the one you most likely use in 95% of all cases). There are other directories for other runlevels (e.g. /etc/rc3.d for runlevel 3, etc.).

VNC (Virtual Network Computing) via ssh

Sat, 26 May 2007 00:00:00 +0000

I am sitting at home and want to use the GUI of my Linux at work. But my work computer which is running the VNC server (mcblpc2.hi.helsinki.fi) is behind the University firewall. The only connection I can get into the firewall is via one of the university mainframes, e.g. vesuri.helsinki.fi. In order to connect using VNC, I need just two commands:ssh -L 5901:mcblpc2.hi.helsinki.fi:5901 mjeltsch@vesuri.helsinki.fivncviewer localhost:1To make the connection faster, you can use compression (helps only if you have a slow connection, e.g. a modem). When using VNC with ssh, the vncviewer really thinks you make a connection to the local machine and therefore chooses a wrong encoding. So the second command actually should be: vncviewer localhost:1 -compresslevel 0 -encodings "copyrect hextile"When you run the vncserver on a computer that has its own firewall, you need to have sshd running and to open the ssh port (22). Then you establish a tunnel from that ssh server on that computer to a port on your local computer:ssh -L 5901:remotemachine:5901 username@remotemachine vncviewer localhost:1When you run KDE desktop sharing on Suse 9.0, you share the physical screen (:0). Thus, if you are logged out, you cannot connect using desktop sharing. You have to start up additionally a vnvserver instance:vncserverThis server will use by default the :1 session and that’s why the forwarded port must be 5901 and not 5900 (like for the first session).

VNC server (aka KDE Desktop Sharing) under Suse 9

Thu, 24 May 2007 00:00:00 +0000

Suse 9 has an inbuilt VNC server called KDE Desktop sharing (under the System -> Remote Access menu). It can be configured in the Control Center -> Internet & Network. Unlike when you start up VNC via the command line (“vncserver”) this tool doesn’t start a new X desktop, but connects to your already existing X desktop. It is possible to run in addition to the inbuilt KDE Desktop Sharing a normal vncserver that starts its own X sessions.

VNC server under Suse 9

Thu, 24 May 2007 00:00:00 +0000

I tried to use vncserver on Suse 9, but to my surprise upon starting up with “vncserver” and then connecting with the “vncviewer” command I only saw the grey screen and an X terminal. I tried to execute xclock and gaim and they start up nicely. However I would also like to bee able to start up KDE. So I looked into the xstartup file (in the .vnc directory in your home folder) from my old Red Hat 9 install and compared it to the one from my Suse 9 install:Suse 9:!/bin/shxrdb $HOME/.Xresourcesxsetroot -solid greyxterm -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &twm &Red Hat 9:!/bin/shRed Hat Linux VNC session startup scriptunset SESSION_MANAGERexec /etc/X11/xinit/xinitrcI figured out that twm is a window manager; thus it replaces KDE in this context. If I replace the Suse script by the Red Hat script, KDE starts up upon starting vncserver.

Using ssh in scripts (one-click secure VNC connection using krdc)

Thu, 29 Mar 2007 00:00:00 +0000

Using ssh in scripts (one-click secure VNC connection using krdc) I wanted to establish a VNC connection that is tunneled via ssh and just by one click. I created a shell script with the following content: !/bin/sh ssh -L 5902:192.168.0.7:5902 -f -N jeltsch@192.168.0.7 krdc localhost:2 The ssh connection remains open in the background until the krdc application has finished.