The X Window System manual page refers to another kind of security called magic cookie authentication, which is more secure than the xhost command. Why isn't it discussed here?
The magic cookie method of authentication is indeed more secure than the xhost command method, but it requires the use of several additional commands, as well as the use of a secure means of network communication to transfer the security tokenusually ssh. When you use ssh to display applications remotely using the techniques outlined in this chapter, the magic cookie authentication method is automatically used for you anyway. In fact, ssh makes the process still more secure by encrypting all network transmissions. Because the magic cookie process is somewhat difficult to implement by hand and ssh automates it so well with added security to boot, you should simply use ssh whenever you can.
Is the remote display facility limited to a one-to-one relationship? That is to say, can I display applications from multiple remote machines on my local display, or can I display local applications on a variety of remote displays simultaneously?
Yes. There is no limitation on the number of systems that can be involved in remote display connections; it is only required that systems have permission to connect to one another. This permission can be granted using either xhost or ssh, as described.
I'm still a little unclear on the basic concept. For example, if I open a file dialog box on a remotely displayed application, which system's files will I see?
Only the application window itself is displayed remotely; all other aspects of the running program occur on the system where the program was launched. So, if a program running on newton is displayed on workstation20 and a file dialog box is opened, the files on newton appear in the file dialog box, even though the file dialog box itself appears on the display of workstation20. Remote display is simply a way to use a desktop application from a distance, taking advantage of network technology to accomplish this task.
Does Fedora Core 4 support VNC? I want to be able to share my desktop with Windows and Mac users.
Yes. The Xvnc command can be used to start a VNC server on your desktop that remote users can use to access your computer. Consult the Xvnc manual page for more information. The native X11 desktop sharing tools are discussed in this chapter because they provide more functionality to Unix users and are somewhat more network-efficient.