12.13 Complex GUI Dial-In, VNC
At the opposite extreme to the simple (but labor intensive) manual dial-in described above, is one that results in GUI graphical interface to the Linux PC. This generally requires that a network running TCP/IP protocol exist between the two computers. One way to get such a "network" is to dial-out to a PC set for dial-in and then run PPP on the phone line. PPP will use TCP/IP protocol encapsulated inside the PPP packets. Both sides must run PPP and mgetty can be configured to start PPP as soon as the caller does. The caller may use a PPP-dialer program just like they were dialing an ISP. Programs such as wvdial, eznet, or chat scripts should do it.
Instead of this tiny network over a phone connection a much larger network (the entire world) is reached via an ISP. For their lowest-rate service many of them use proxy servers that will not give you access to the ports you need to use. Even if they don't use proxy servers, the IP address they give you is only temporary for the session, so you'll need to email this IP to whomever wants to reach you. If you get a more expensive ISP service, then you can avoid these problems.
One way to get a GUI interface from the remote PC is to run the GPLed program: Virtual Network Computer (VNC) from AT&T. It has a server part which you run on your Linux PC for dial-in and a viewer (client) part used for dial-out. Neither of these actually does any dialing or login but assumes that you have a network already set up. The VNC server has an X-server built in and may use Linux's twm window manager. See the article on VNC in Linux Magazine: http://www.linux-mag.com/2000-11/desktop_03.html. The AT&T site for VNC is: http://www.uk.research.att.com/vnc/.
With VNC one can also connect to remote Windows PCs, get the Windows GUI on a Linux PC, and run Windows programs on the remote Windows PC. Of course the Windows PC must be running VNC (as a server). Obviously, a GUI connection over a modem will be slower than a text-only connection especially if you run KDE or GNOME or want 16-bit color.
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