Virtual Network Computing (VNC) allows you to access and control a graphical desktop running on one machine from another. This permits you to seamlessly use a desktop environment and graphical applications while not having to sit infront of the physical keyboard / mouse attached to a computer.
This can also be accomplished via ssh, as most ssh servers have this enabled by default, you merely need to specify "-X" or "-Y" to ssh when connecting and then run your graphical application. Comparilively, VNC is nowhere near as secure and takes a few steps to setup, but is greatly faster (afterall over ssh, every single draw command needs to be sent over an encrypted connection) and allows you to run and view a full desktop environment as opposed to just individual applications.
VNC is relatively easy to setup, albeit with a few caveats, as described below:
(edit 07/07/09, a few things changed w/ the vnc-server shipped with Fedora 11, see my note at the end of this post)
- Install it: "yum install vnc-server"
- Edit /etc/sysconfig/vncservers, and add the following two lines:
VNCSERVERARGS="-geometry 1024x768 -nohttpd "
Replacing username with a valid user that can log into the system. Also specify any screen resolution supported by X on your system. The '-AlwaysShared' flag can be specifed to permit sharing the vnc connection among multiple clients. Finally you can add as many servers as you want here, each with its own options. (07/07/09 see note below)
- As the aformentioned user run the 'vncpasswd' command and provide a password. You will be prompted for this when you connect to the vncserver
- Open the necessary port(s) for remote access. Accomplished via 'system-config-firewall' (or 'system-config-firewall-tui' for the text / ncurses version), open up the port corresponding to each server you create. By default this port is 5900 + the server number, for example 5902 for the server configured in step 2 above. You can override this with the "-rfport" option in the aformentioned server options.
- Edit the aformentioned user's ~/.vnc/xstartup config file to launch the desired desktop environment and/or window manager upon server instantiation. By default, a barebone 'Tabbed Window Manager (twm)' is launched, and most likely you will want gnome, kde, or something else. Simply comment out the last line, "#twm &"; and uncomment the two which you are directed to uncomment in the file itself, eg. 'unset SESSION_MANAGER and ' 'exec /etc/X11/xinit/xinitrc'. This will launch the desktop env / window manager configured as default systemwide.(07/07/09 see note below)
- Make sure vnc as part of / launched by xinet.d is disabled, else you will get "A vnc server is already running as :2". This can be accomplished by editing /etc/xinet.d/vncts and setting all 'disable' options to 'yes'. You will need to restart xinetd by running 'service xinetd restart'
- Finally start the vncserver by running 'service vncserver start'
Now you should be able to connect to it on another machine by installing the client package 'yum install vnc' and executing it via 'vncviewer server:2' (which will prompt you for the aforementioned password).
And whala! Remote graphical access!
[Update 07/07/09: If running F11 or later, make the following changes to the process above:
- in step 2 above, the "-nohttpd" option is no longer supported and the vnc service will fail to start if present
- step 5 above is no longer needed, vnc will default to the window manager you normally use]