<div dir="ltr"><div>Hi, Christopher Barry: </div>Thank you for the reply. But this is not the answer I want. Actually I did't see any relation between my question and that link. I think I have clearly specified what the answer is expected. Please leave the slot to other experts. Thanks. </div><div class="gmail_extra"> <div class="gmail_quote">On Wed, Dec 31, 2014 at 8:57 AM, Christopher Barry <<a href="mailto:christopher.barry@earborg.com" target="_blank">christopher.barry@earborg.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="HOEnZb"><div class="h5">On Tue, 30 Dec 2014 21:05:18 -0500 Heng Zhou <<a href="mailto:hzhou1@cs.uml.edu">hzhou1@cs.uml.edu</a>> wrote: >I want set up an environment in which a local X server is connecting a >remote display manager via XDMCP protocol, just like the second >picture in the wikipedia item "X display manager" ( ><a href="http://en.wikipedia.org/wiki/X_display_manager_%28program_type%29" target="_blank">http://en.wikipedia.org/wiki/X_display_manager_%28program_type%29</a>) >shows. The specific configuration is described in the following. > >A computer is running ubuntu 14.04 LTS in front of me. Call it "local >machine". > >A headless server is running ubuntu 14.04 LTS at another geographical >place. Call it "remote machine". The remote machine has no graphics >card, no attached monitor, but I have full control over it. >Concretely, it is an Amazon EC2 ubuntu instance. > >The local machine has a physical graphics card and an attached >monitor. It is running ordinary ubuntu desktop so the X Window System >-- X.Org Server -- is running after boot, presumably. > >The remote machines has installed LightDM, the display manager of >ubuntu. And I am sure it is running over there by checking the results >returned by command ps aux|grep lightdm. > >That's the configuration of the local and remote machines. Now I need >to follow the steps in the wikipedia item "X display manager" (please >see the link above) to try to connect the local X server with the >remote display manager LightDM. What I wish to happen should be, >according to my understanding of the wikipedia webpage, as follows: > >(1) The local machines run a XDMCP Chooser program to select the >display manager running now on the remote machine to connect. > >(2) The X server on the local machine uses XDMCP protocol to shake >hands with the remote display manager LightDM. > >(3) The remote display manager LightDM should respond as expected: > >a) it connects to the local X server as a client > >b) display a login GUI on the local machine, with the assistance of the >local X server > >c) start an X session after I log in > >d) run X applications like xterm in the session as directed; display >its graphical output on the local machine, using the local X display >server. > >e) If possible, I hope in addition to show the unity desktop on the >local machine, just like a normal ubuntu desktop, but the executable >code is actually running on the remote machine. > >That's all I want. But I have no idea how all these can be done. I >searched the internet and found something like ><a href="http://wiki.ubuntu.com/xdmcp" target="_blank">http://wiki.ubuntu.com/xdmcp</a> and ><a href="http://danilodellaquila.com/blog/how-to-remote-login-via-xdmcp-in-ubuntu" target="_blank">http://danilodellaquila.com/blog/how-to-remote-login-via-xdmcp-in-ubuntu</a>, >but they are either too old or too too old, and therefore useless for >my configuration. So I wonder if anyone familiar with XDMCP and having >a workable experience could please share his/her ideas on how to >setting up this environment. Please be specific. Thanks a lot. If you >need any other info, please ask. > >PS: The display manager on the remote machine doesn't have to be >LightDM. I specifies it just because it's light weight and I'm >familiar with ubuntu desktop. You can use other option, say, GDM, if >you are working or once worked with it, to set up the environment. > >Looking forward to any workable instructions. Thanks. </div></div>See: <a href="http://ltsp.org/" target="_blank">http://ltsp.org/</a> -- -C </blockquote></div> </div>