XDMCP on antiX

mckemie · posted: 2011-11-12 13:16

Has anyone used XDMCP on antiX? I find that the most attractive way to run remotely. It seems it should be especially attractive to antiX users of very old boxes. Back about version 8, it worked very well on Ubuntus. More recently, they've screwed it all up.

oldhoghead · posted: 2011-11-13 15:42

mckemie,

I have not used xdmcp, but I have used Teamviewer, works cross platform, very simple, free and secure. I use it to update my step-son's Windows computer and can access my desktops, laptops etc if I need to. I have no affiliation or connection to this product.

Check it out:

========= SCRAPER REMOVED AN EMBEDDED LINK HERE ===========
url was:"http://www.teamviewer.com/en/index.aspx"
linktext was:"http://www.teamviewer.com/en/index.aspx"
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cheers,
ohh

mckemie · posted: 2011-11-14 13:45

Thanks, I was not previously aware of teamviewer. A most interesting product. It appears to be a commercial product which they would likely be trying to collect fees for. Eventually. It also appears to display through a browser. Nice that it can conveniently get through firewalls and be used over the internet. My need is for something to work only over my LAN. And, I have no need for cross-platform stuff that makes vnc and teamviewer more complex.

X has all this wonderful remote operation stuff built in. Seemingly, VERY under utilized. Many do not know to run remote X applications on the current display by first"ssh -XC <user>@<ip>". Many may not realize that X has multiple displays, switchable via a keystroke combination; just like virtual consoles.

A little research has revealed (to me, I guess you all already knew that) that slim is the anitX login/display manager and does not support remote logins. When I get around to an antiX install, I will try a xdm install and see where that goes. XDMCP gives one a complete remote display; nothing on the display from the local box. Except for speed, it is just like being in front of the remote.

It seems to me that X remote stuff is well suited to antiX since it allows one to make use of high end boxes from multiple boxes of very modest capability.

oldhoghead · posted: 2011-11-16 15:14

I did read about that ability in a book I have"Linux Desktop Hacks" 2005, so a little dated but still relevant is some ways. Well, good luck on your foray into XDMCP, and keep us posted, you might want to keep good notes and do a how to, maybe get it included in the next version of antiX documentation.

cheers,
ohh

plvera · posted: 2011-11-16 20:06

I am interested in this so I did a little bit of reading. From what I found, slim does not support xdmcp

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url was:"https://wiki.archlinux.org/index.php/Xdmcp#SLiM"
linktext was:"https://wiki.archlinux.org/index.php/Xdmcp#SLiM"
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However, GDM does. So, one could install GDM (which I have done in antiX and it runs quite well) and then set it up for xdmcp. Here's an excellent how to. Part 4 is about linux to linux connections, but it starts out with steps in part 3 where you set up GDM for xdmcp.

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url was:"http://linux.koolsolutions.com/2009/05/01/linux-remote-desktop-part-4-connect-to-remote-linux-server-with-xdmcp-protocol-from-another-linux-machine/"
linktext was:"http://linux.koolsolutions.com/2009/05/ ... x-machine/"
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I might give it a test run.

EDIT: I forgot to mention that once you install GDM you can't use slim.

mckemie · posted: 2011-11-17 23:28

This jogged my memory a bit on how XDMCP is supposed to work. A"server" (X folks are likely to call it a client) must have XDM/KDM/GDM properly configured to provide an X display to a thin client such as antiX might be used for. I have at least one old Ubuntu box so configured. Newer Ubuntus are more difficult or impossible to configure to provide X displays remotely. antix might work"out of the box" to do a remote X display, though adding XDM/KDM/GDM would allow one to go directly to the remote display rather than first doing a local display.

I just tested the only antiX I have semi-working, via Live CD, and failed to find joy. From a root terminal:
X :1 -query <IP of X server/client>
After switching to display :1, it hangs. I can <ctrl><alt>F7 back to display :0.
Could not like doing it from a LiveCD. Could be lack of memory. Could be something else. Bad luck. Bad Karma.

BitJam · posted: 2011-11-18 05:05

This looks really cool!

I'm running gdm on my Gentoo box so I checked this out. I added two lines to the custom.conf file under /etc/X11/gdm:

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[security]
DisallowTCP=false

[xdmcp]
Enable=true

I restarted gdm and was able to get a new gdm login screen on the same machine via:

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# X :1 -query localhost

If it's not working remotely maybe the problem is a firewall. You might need to open up port 6000 on the machine running gdm. I'd be concerned about security though.

If you think it might be a memory problem, you can boot directly to the console (no X-windows) by using the boot parameter"3". This starts you up in run level 3 which has no X. You can use <Alt>+<Left-Arrow> and <Alt>+<RIght-Arrow> to move between virtual consoles. The"free -m" command will tell you how much memory has been used and how much is available but the htop program might be much better.

You can try installing nmap on your Ubuntu system and then run:

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$ nmap -A <IP of machine running gdm>

When I did this on my machine, I got:

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$ nmap -A localhost 

Starting Nmap 5.51 ( http://nmap.org ) at 2011-11-17 21:48 MST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00054s latency).
Not shown: 995 closed ports
PORT     STATE SERVICE      VERSION
25/tcp   open  smtp         Postfix smtpd
80/tcp   open  http         Cherokee httpd 1.2.101 (Gentoo)
631/tcp  open  ipp          CUPS 1.4
783/tcp  open  spamassassin SpamAssassin spamd
6000/tcp open  X11          (access denied)
Service Info: Host:  localhost; OSs: Linux, Unix

Service detection performed. Please report any incorrect results at http://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 6.32 seconds

There are web sites you can go to that will perform a similar scan but I wonder if this might be just asking for trouble. If you have a firewall in a router between you and the net, you could temporarily disable the firewall, have the web site perform the scan, then re-enable the firewall.

If you get this working on antiX, I'd be very curious to know how it affects resource consumption.

Edit: Correct a comment about the nmap output.

BitJam · posted: 2011-11-18 09:00

Success! I had to disable the firewall on the machine running gdm. I tried just opening port 6000 but that didn't help. When I couldn't connect, the graphic display would start but I would just get a blank screen. I then used <Ctrl><Alt><F2> to get back to the console I ran the X command in and hit Ctrl-C to abort the program.

When the firewall was disabled I was able to connect to gdm with the command you gave. It just worked. Here are the stats:

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No X running:  27 Meg used
X running locally: 51 Meg used
X running remotely: 32 Meg used

Of course, when apps start getting used, the usage when running X locally will grow much faster then when X is running on a remote machine.

This is very cool but I am concerned about the security. IMO you only want to use this on a LAN that has it's own firewall blocking access from the net.

I might try going the other way so I can log into my antiX box from my Gentoo box.

mckemie · posted: 2011-11-20 16:15

I tested my very limited antiX/test/flex which will boot on my Compaq Armada 7xxxs and found that X remote logins work just fine. I even ran two, one on display :1 and one on :2, concurrently. Of course with a liveCD things go very slowly and, without a display manger that supports XDMCP, I have to first bring up X on the local. I look forward to getting an antiX on which I can do a hard drive install.

I have noticed that the default antiX colors and/or fonts lack legibility on my 1024x768 display; poor contrast and too small characters. The Ubuntus that I am remote displaying continue to look fine.

Edit: It was several days ago I first tested and I have no explanation as to why the first test failed and the second succeeded. They are on two different but almost identical laptops. I did rob the wifi card out of the first to get the second connected to my network.

BitJam · posted: 2011-11-20 19:02

mckemie wrote:I have noticed that the default antiX colors and/or fonts lack legibility on my 1024x768 display; poor contrast and too small characters. The Ubuntus that I am remote displaying continue to look fine.

Normally I would instruct you to use the dpi=xxx boot option, trying dpi=110 as a first stab. This adjusts the"dots per inch" and allows you to change the size of fonts in X-windows. But this won't work for you because we only modify the SLiM display manager configuration and by using XDMCP you are bypassing SLiM. You could trying running:

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$ xrandr --dpi 110

from within a terminal window. I just get an error message about"size of gamma". Maybe it will work for you.

Another approach is to edit your /etc/X11/xorg.conf and inside the:

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Section"Monitor"
...
endSection

add a line like:

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     DisplaySize 236 177    # In millimeters

which will/should give you 110 dpi at a resolution of 1024 x 768.

You can try to install to your hard drive with the test iso. Some things will be missing. Some things may be broken. Just let people know what you are using when you ask for help. If the install works then you will be no worse off than you are now and it should be much much faster. H'mm. I just realized that the install will probably not work because you need the triflex driver to talk to the hard drive.

I predict that you should be able to install but you won't be able to boot the new installation. I'd bet you would get a kernel panic right away. I'm pretty sure I know how to fix this but I'm not sure of the best way to get the solution to you. You wouldn't have to re-installed. We would just have to make a few tweaks to what is already there.

If you don't mind being a guinea pig, I'd suggest that your try installing and then let me know the results.

mckemie · posted: 2011-11-20 20:38

BitJam wrote: You can try to install to your hard drive with the test iso. Some things will be missing. Some things may be broken. Just let people know what you are using when you ask for help. If the install works then you will be no worse off than you are now and it should be much much faster. H'mm. I just realized that the install will probably not work because you need the triflex driver to talk to the hard drive.

I predict that you should be able to install but you won't be able to boot the new installation. I'd bet you would get a kernel panic right away. I'm pretty sure I know how to fix this but I'm not sure of the best way to get the solution to you. You wouldn't have to re-installed. We would just have to make a few tweaks to what is already there.

If you don't mind being a guinea pig, I'd suggest that your try installing and then let me know the results.

I did attempt an install a day or two after you supplied the"test/flex" (as I've been referring to it) ISO. I failed and don't recall the details. Can try again if you wish. Would need to again identify a drive I'm willing to overwrite. You advised that a"real" release would be available soon. The"test/flex" is the only antiX ISO I have that will boot.

BitJam · posted: 2011-11-20 23:19

mckemie wrote:I did attempt an install a day or two after you supplied the"test/flex" (as I've been referring to it) ISO. I failed and don't recall the details. Can try again if you wish. Would need to again identify a drive I'm willing to overwrite. You advised that a"real" release would be available soon. The"test/flex" is the only antiX ISO I have that will boot.

It is possible/likely that a real release won't solve your installation problems. It is more likely to solve problems with broken or missing apps.

I'd be interested to know where the install process fails.

mckemie · posted: 2011-11-20 23:41

Doing this from a remote X display on antiX!

On an antiX terminal,
xrandr --dpi 110
gave me the same (non) result.

On the antiX display, I right click, chose"install", a pop up ask for root password, I give it"root", then nothing else.

anticapitalista · posted: 2011-11-20 23:52

Use the cli-installer out of X if you have low RAM and an old CPU. (type cli-installer as root user)

BitJam · posted: 2011-11-21 01:02

@anti, I just composed an email to you about this. Willie is going to need to use the"initrd" option during the install in order to get the triflex driver loaded during the boot process. Is this option available in the cli installer?

I looked inside an initrd.img-2.6.36-1-mepis file from a /boot directory and it looks like it will load ALL hard-drive drivers (if modules=most is set) which should solve Willie's triflex driver problem on install. Of course, he would need a version that matches the kernel he is using.

@Willie, if there is an initrd option available during the install, say"yes". If it asks you about modules, say"most" (if that is an option).