GUI access servers are most useful when a computer's primary function is to provide workstation-like functions to multiple or remote users. For instance, a company with a dozen employees might purchase one high- powered central system and a dozen much less powerful computers that function as GUI terminals for the central computer. This central system could host applications like StarOffice, The GIMP, KMail, and so on. Individuals would sit at the less-powerful systems, log into the central system, and run their applications remotely. Compared to an environment in which individuals sit at workstations that run their programs, this configuration offers several advantages, including:
Of course, a network configured in this way has its drawbacks, as well. Most importantly, the reliance upon a single computer means that if that system goes down, all the other computers become effectively useless. If you decide to configure a network in this way, you should be particularly diligent about backing up the central system, and have spare parts on hand in case of a failure. You might even want to configure a computer as a backup, ready to take over the primary system's duties on a moment's notice.
Even if you aren't configuring a large network for which you want to use a central system to handle all normal user logins, you might want to use a GUI login tool to allow smaller-scale or peer-to-peer logins. All your users might have their own workstations, for instance, but if they occasionally need to do work from remote locations, those workstations can be configured to accept remote accesses , allowing a user to work from another user's workstation, from home, or from some other location.
Remote GUI access tools are most often used on a local network. Because GUI displays transfer a great deal of data, the use of these protocols across the Internet at large often results in a sluggish display. Indeed, even on a local network with 100 Mbps hardware, GUI protocols are noticeably slower than local GUI displays, although the speed on a local network is usually acceptable. As with text-based remote access tools, GUI tools provide users with full login privileges, and a password must be exchanged, so there are security risks to running such protocols. (The VNC tools encrypt passwords but not regular data, reducing risks slightly. Using SSH for the initial login allows you to encrypt the password and all session data.)