LINUX AND XDMCP

[Joe Sullivan]

Hello...

I have recently been given the opprotunity to expand my bandwidth and be a linux admin.

I currently like to use X windows with my unix machines by via the XDMCP broadcast using Reflections X emulator.

I'm having great difficulty getting my linux server (redhat enterprise release 4 update 6)
to accept xdmcp broadcasts.

I've read a wonderful article that i thought was going to solve my problems. A redhat xdmcp howto by Thomas Chao. It didn't.

Any other publications/howto/recommendations would be appreciated.

Thanks...

[Justin_99]

I have got it to work in the past, don't Think I did much more than run gdmconfig and turn on xdmcp and unchecked always disallow TCP connections to X server.

[Ivan Ferreira]

Normally, running at runlevel 5, running gdmsetup to enable XDMCP and gdm-restart to reload the configuration should be enough.

[Rick Retterer]

Joe,

I'm not one to tell you what to run on your PC or Linux system, but I'll tell you it's much easier to setup XVNC on Linux and use it than it would be to setup XDMCP.

To setup Xvnc, Telnet into your system or ssh into it as you normally do, and execute the command to create a Xvnc Password...

#/usr/bin/vncpasswd

Follow the prompts...

This will create a hidden directory in your $HOME directory named .vnc

Next, you will want to startup Xvnc so that it will create the necessary files you will need to modify to run a session.

# /usr/bin/vncserver :1

This will then startup the server on your system on ports: 5901 and 5801.

Shutdown the server using this command:

# /usr/bin/vncserver -kill :1

Now, change directory into your .vnc directory and vi the file named "xstartup".

#!/bin/sh

# Uncomment the following two lines for normal desktop:

unset SESSION_MANAGER
exec /etc/X11/xinit/xinitrc

[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
[ -r $HOME/.Xresources ] && xrdb

$HOME/.Xresources
xsetroot -solid grey
vncconfig -iconic &
xterm -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
#twm &

Once you have uncommented the two lines, save the file and exit your editor.

Now, restart the vncserver again just like before...

# /usr/bin/vncserver :1

It will start the server and then load your desktop.

Now, all you need to do is to bring up a web browser on your PC and connect to your system by specifying the port you started your session on.

http://your.rhel.system.address:5901/

This will then connect to the vnc server using the port you selected, 5900 + your port number you started the server on.

If you had used port # 3, then you would use this port number on your URL.

http://your.rhel.system.address:5903/

When the login prompt comes up, enter the password you created with the "vncpasswd" tool, and wait for the session to come up in your browser.

Now, if you don't like using the browser, you can download a VNC client tool such as TightVNC or one of the others and it will allow you to run VNC on your PC just as if it were running using ReflectionsX.

You can also setup the VNCSERVER to startup at boot time on your Linux system, by modifying the file located in /etc/sysconfig/vncservers

In this file you simply add your username, and the server number you want your server to startup on.



Example:

"vi" the file /etc/sysconfig/vncservers

Read the comments in the file.

VNCSERVERS="3:retterer"
VNCSERVERARGS[3]="-geometry 1280x1024 -depth 16"

Save the file and exit vi.

Make sure that you use the "services" utility and enable VNC Servers to startup
VNC at boot time.

If you have any questions, be sure to read the man pages on Xvnc, vncserver, vncpasswd and any other vnc components listed in the man pages.

Please have a look at these websites for details about the information that I have provided to you here.

http://www.rhic.bnl.gov/RCF/UserInfo/Software/VNC/vnc.html

http://bobpeers.com/linux/vnc.php
http://www.linuxtopia.org/HowToGuides/VNC_setup_Linux_Windows.html

Here is the link to TightVNC
http://www.tightvnc.com/download.html

Good Luck to you, I hope you find VNC as useful as I do.

Cheers,
Rick Retterer

[Rick Retterer]

I made a error in the port number, you should connect using port 58xx.. for example 5803.

58xx is the ports used for browsers and such
59xx is for the vnc client connections like tightvnc.

Sorry about the mixup.

Cheers,
Rick

[Alan_152]

Here's an article I used quite a bit when I used XDMCP -- http://www.starnet.com/xwin32kb/How_do_I_enable_XDMCP_on_my_Unix_machine/

However, I've since gone on to just using Cygwin-X with putty -- http://x.cygwin.com/ -- I'm not sure why its unmaintained, since everyone I know uses it rather than paying for ReflectionX or Exceed.

Other options include VNC (mentioned previously, though I think it is dog-slow) and xrdp (http://xrdp.sourceforge.net/)

[tony j. podrasky]

My MASTER host is called M2404TXP.

My LAPTOP that gets a login window on it that says "welcome to M2404TXP" is HAMMY.


HAMMY has the following entry in its /etc/inittab file:

# Run xdm in runlevel 5
x:5:respawn:/usr/bin/X11/X -query m2404txp

When I want to use HAMMY by itself I start it up in init 4.

When I want HAMMY to be a login device to M2404TXP I do and the login window from M2404TXP appears.

--

If you go into /etc/X11/xdm you'll find some files that need to be tweaked.

I don't remember what all - but they are simple ASCII text files - and if you like, I can make a tarball of them and e-mail them to you. The whole directory is only 176KB. REMIND ME to include the /etc/rc.d/init.d/xdm file as well.

If you'd like them, send me e-mail at hunybuny@eskimo.com

(eskimo.com is a Linux-friendly site).

regards,
tonyp

[~sesh]

Perhaps you could check the documention from RedHat, you can find it here:

http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/s390-multi-install-guide/s1-trouble-after.html#S2-TROUBLE-REMOTEX

AND

http://kbase.redhat.com/faq/FAQ_85_9053.shtm

[~sesh]

Any luck Joe?