The following is from a thread from this past week, but to save you time i have included it below.
Hope this is what you were looking for: Please note that this should not be done over a public network as XDMCP is not a very secure protocol. ===Begin Paste=== Andy, you rock... Thanks a bunch. All the information you provided is accurate and functional. As far as the security concerns you mentioned all of the hosts involved in this config are in a R&D environment on non-routable nets. Otherwise I would just use ssh. For any that are running RH9 there is also another way to get the same results. I found this after about 6 hours of reading. This is for systems running RH9 and Gnome as the desktop. The file /etc/X11/gdm/gdm.conf contains config paramters for xdm (gdm), xdmcp, and the login screen you see when you start an X session. Look for the '[servers]' section The default server config is: '0=Standard' comment that line out and add a line that looks like this: '0=Terminal -indirect serverhostname' (in my case it was jupiter) This sets up your client machine to send an indirect X query to 'serverhostname' to find out what X servers are available. On the 'serverhostname' (jupiter) you need to configure it so that it replies to the query with a list of X servers that are accessible to handle the request. The configuration is done via a file called /etc/X11/xdm/Xaccess There are a number of ways Xaccess can be configured depending on your needs. The file is pretty well commented so it is easy to understand. Also, for additional information - which was also very helful I managed to find a tutorail about all of this that even a neophyte like myself can understand. http://www.menet.umn.edu/~kaszeta/unix/xterminal/basics.html WARNING: If you do read the documentation about XDMCP you will learn that it is NOT a very secure protocol and if you plan on implementing this config over a public network you need to take additional security measures. Many thanks to Andy, and the author of the link above... Now when I boot Linux is presents me with a screen that enables me to choose which linux box I want to initiate an X session for. Very cool. OSUniverse PS. The documentation for XFree86 makes the book 'War and Peace' look like a short poem, no wonder people would rather fight wars than learn computers. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Andy Goth Sent: Wednesday, June 25, 2003 10:45 PM To: [EMAIL PROTECTED] Subject: Re: [XFree86] X-ing to other hosts On Tuesday, June 24, 2003 10:32 pm, News/Info wrote: > Psuedo-newb here... > > Two hosts mars and jupiter both have linux and XFree installed, both work > fine and without incident. My objective would be to use just mars and be > able to start an X session on either mars or jupiter without having to go > back and forth between two keyboards. > > Suggestions? > How is this done...? Set the DISPLAY environment variable or use the -display option of your client application to specify which X server to connect to. Examples: $ xterm -display jupiter:0 $ DISPLAY=mars:0 xclock The number after the colon says which numbered server to connect to, in case you run multiple servers on the same machine. If one server manages multiple screens (like if you use a multihead configuration without xinerama), add a period and a screen number, as in xterm -display jupiter:0.0 > What config is required on jupiter to allow X access from mars? jupiter$ xhost + mars > What config is required on mars to enable me to launch an X session on > either mars or jupiter? mars$ xhost + jupiter But I'm not sure I understand your question correctly... Please somebody explain to the both of us how real X security is attained. The above method (xhost) makes many insecure assumptions: - You are the only person with shell access to either mars or jupiter. - It is impossible for anyone to pretend to be mars or jupiter. - Neither mars nor jupiter contain malicious or buggy scripts that can play havoc with your X server. At my university, they make the fatal mistake of having their NCD X servers grant host-based access to the #1-used UNIX server on campus. This allows me to make my friends' mouse pointers turn to Gumby, but it allows anyone at all to track your keystrokes or even execute arbitrary code as you through stuff like the send command in Tcl/Tk. -- Andy Goth | [EMAIL PROTECTED] | http://ioioio.net/ End communication. _______________________________________________ XFree86 mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/xfree86 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Ross Vandegrift Sent: Friday, June 27, 2003 3:20 PM To: [EMAIL PROTECTED] Subject: [XFree86] Multiple local xdm displays Hey everyone, I'm trying to configure my xdm to start two local X servers - one local login, and one remote. My Xservers file looks like: :0 local /usr/X11R6/bin/X :0 vt7 -dpi 100 -nolisten tcp :1 local /usr/X11R6/bin/X :1 vt8 -dpi 100 -query remotehost I can't see why this shouldn't work - if I only configure xdm to do :0, and I start :1 by hand from the console, everything works fine. I *suspect* xdm freaks because two Xservers are simultaneously trying to mess around with video hardware (the console goes crazy while xdm is trying to start this configuation). Is there a way I can stagger the starts by a few extra seconds? I've tried setting DisplayManager._1.openDelay to something large like 100, thinking: 1) :0 and :1 will start, one will fail. 2) :0 will (perhaps retry and then) finish starting 3) :1 will try 100 seconds later and work fine But the net result is that :1 is never started. FWIW, this is Debian testing, SIS513, XF86 4.2.1.1, with the sis driver and no fbcon. -- Ross Vandegrift [EMAIL PROTECTED] A Pope has a Water Cannon. It is a Water Cannon. He fires Holy-Water from it. It is a Holy-Water Cannon. He Blesses it. It is a Holy Holy-Water Cannon. He Blesses the Hell out of it. It is a Wholly Holy Holy-Water Cannon. He has it pierced. It is a Holey Wholly Holy Holy-Water Cannon. He makes it official. It is a Canon Holey Wholly Holy Holy-Water Cannon. Batman and Robin arrive. He shoots them. _______________________________________________ XFree86 mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/xfree86 _______________________________________________ XFree86 mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/xfree86
