How do you allow remote X connections in FreeBSD

baronobeefdip · 07-30-2012, 01:48 PM

I want my FreeBSD box to allow remote tcp connections to the X server, I am wanting to control the X server on the other computer from mine remotely. I know that this connections is tcp protocol and operates on port 6000, I also know that this isn't enabled by default (For security reasons) How do you enable this (without the help of the GUI, I am only installing the Xorg display server on the machine from the packages on the DVD)

Reuti · 07-31-2012, 02:55 AM

Check the command man xhost.

baronobeefdip · 07-31-2012, 10:52 AM

I already ran an Xhost on the client (xhost +<ip of server) and I rebooted it. The I ran that Xdmx command again to connect to the client and it still won't let me. So the simple problems don't seem to be the problem. I also checked the firewall (in case someone decides to bring that up) but it won't hurt to show me how to shut down the firewall and open up port 6000

Emerson · 07-31-2012, 07:34 PM

Quote:

Originally Posted by baronobeefdip

I want my FreeBSD box to allow remote tcp connections to the X server, I am wanting to control the X server on the other computer from mine remotely. I know that this connections is tcp protocol and operates on port 6000, I also know that this isn't enabled by default (For security reasons) How do you enable this (without the help of the GUI, I am only installing the Xorg display server on the machine from the packages on the DVD)

Not sure what you mean.

Do you have an X application you want to run remotely?

In this is the case you need to install this app in remote box with supporting libraries and run it. Remote box does not need X to be installed. Your local box needs X to be run allowing incoming TCP connections.

baronobeefdip · 07-31-2012, 08:58 PM

Quote:

Originally Posted by Emerson

Not sure what you mean.

Do you have an X application you want to run remotely?

In this is the case you need to install this app in remote box with supporting libraries and run it. Remote box does not need X to be installed. Your local box needs X to be run allowing incoming TCP connections.

How do I make the remote box allow tcp connections? I figure that you need to set this on the machines that will be controlled remotely. Not the one that you are controlling the Xorg display servers with. (Correct me if I'm wrong. I just ran an xhost on both the local and remote box)

I have been failing to enable the tcp listening in the Xorg servers in Ubuntu and Debian, (It's suppossed to open port 6000 but I don't see it open after running some nmap scans so there must be more to just removing the -nolisten tcp part of the configuration file. I also saw no firewall running so that can't be the problem)

Emerson · 08-01-2012, 06:07 AM

I think you are getting it a little backwards.
X, as most *nix applications is network-aware. (Xorg is not part of FreeBSD nor Linux, it runs great on most POSIX compliant platforms.) Which means an application can be run in one box and the display can be in another box.
Example:
I have a headless FreeBSD box running MythTV backend. To set it up I need to run mythtv-setup, which is an X app. I will not install X on that box, why install all that cruft if the box is headless.
On my desktop I start X with port 6000 open. Easiest way to do it is overriding the system setting (-nolisten tcp) with user setting. This is another feature I love about *nix. No need to fiddle with system files (which get overwritten with upgrades). I just created .xserverrc in my home directory.

Code:

~ $ cat .xserverrc 
#!/bin/bash
exec /usr/bin/X

After restarting X I'm ready to run remote apps. Of course, to allow remote box to connect I use xhost turtle3.
So I log into remote box (it's not important how, SSH is handy) and issue DISPLAY=zeus:0.0 mythtv-setup &.
MytTV setup is displayed on my desktop [zeus] while it is running in the remote box [turtle3], I can close the SSH session, it is not needed any more.

Reuti · 08-01-2012, 06:38 AM

Tunneling via SSH is not an option?

Code:

$ ssh -X -Y remote_machine

baronobeefdip · 08-01-2012, 11:48 AM

Quote:

Originally Posted by Emerson

I think you are getting it a little backwards.
X, as most *nix applications is network-aware. (Xorg is not part of FreeBSD nor Linux, it runs great on most POSIX compliant platforms.) Which means an application can be run in one box and the display can be in another box.
Example:
I have a headless FreeBSD box running MythTV backend. To set it up I need to run mythtv-setup, which is an X app. I will not install X on that box, why install all that cruft if the box is headless.
On my desktop I start X with port 6000 open. Easiest way to do it is overriding the system setting (-nolisten tcp) with user setting. This is another feature I love about *nix. No need to fiddle with system files (which get overwritten with upgrades). I just created .xserverrc in my home directory.

Code:

~ $ cat .xserverrc 
#!/bin/bash
exec /usr/bin/X

After restarting X I'm ready to run remote apps. Of course, to allow remote box to connect I use xhost turtle3.
So I log into remote box (it's not important how, SSH is handy) and issue DISPLAY=zeus:0.0 mythtv-setup &.
MytTV setup is displayed on my desktop [zeus] while it is running in the remote box [turtle3], I can close the SSH session, it is not needed any more.

So your saying this.
To get my apps displayed on a different box remotely I need to enable tcp listening (in the config file mentioned throughout this thread) and ssh into the host and create a .xserverrc in the user's home directory. the restart X (still have no idea on how to do this) then when I run the Xdmx command on the front end (the one that I am using to control the X session on the other box that I hopefully enabled tcp listening on) then I can do with it what ever I please. So now lets assums that I got this working now, how do I get several computers to be remotely controlled by a box and display an entire picture when appended together (a tile display cluster). Unlike other visualization cluster this method requires no setup of the MPI until you start messing with the middleware which make the execution of OpenGL compliant programs possible over the LAN. For now I am only interested in pictures and source (maybe a screen used to show a movie or have coupled with a television tuner, I'll leave the google earth and all that to the middleware)

Emerson · 08-01-2012, 12:39 PM

No.
I must be the worst teacher because you still don't get it.

You are sitting at box A.
Remote box is B.
You enable X server listening in box A. All you need to do is to override systemwide setting in box A by creating .xserverrc in your home and restart X so the new setting becomes in effect. Now box A is listening for incoming connections.
Then you ssh into box B and run the app, setting DISPLAY variable to box A. The app you run in box B will display in box A.

baronobeefdip · 08-01-2012, 02:37 PM

Thats not what I want to do, I want to use box A to control what is being displayed on box B remotely and hopefully use it to control other nodes instead of one and append each of the screens together and it will complete a full image with different parts of the image being displayed on each screen.

I am not looking to do what you mentioned, I want to use the computer I am sitting at to control what is being displayed on the computer I am not sitting at. In order to do this do I need to have the app installed on the box I am not sitting at because all I am doing is transferring images to the computer I am not sitting at through Xorg's protocol across port 600 which is where it listens for packets on.

You told me how to control the images on box A from box B which is the remote, You have it backwards I want to control what gets displayed on the remote box from Box A which will be the box I am sitting at. I also want to be able to see images on box A to allow me to control what is being displayed on box B without having to walk up to box B and try to control it from box A which will be a hassle only having display on the remote machine, I want to see what I am doing from the machine I am sitting at.

Reuti · 08-01-2012, 02:48 PM

Aha, this is indeed possible by setting ”xhost +“ and allow external connections. You define on your local machine then:

Code:

$ export DISPLAY=<remote_machine>:0.0
$ xterm

and the terminal should open on the other machine. But instead you get a timeout or any output in any logfile?

baronobeefdip · 08-01-2012, 03:33 PM

Quote:

Originally Posted by Reuti

Aha, this is indeed possible by setting ”xhost +“ and allow external connections. You define on your local machine then:

Code:

$ export DISPLAY=<remote_machine>:0.0
$ xterm

and the terminal should open on the other machine. But instead you get a timeout or any output in any logfile?

How do I define those allowed local connections on my local machine? I never read how to do that

And how do I gain control of more than one machine and have them display parts of an image but complete the image when I place the screens together, I am trying to make a display wall and I not only want to know how to align the display screens to display the whole image horozontally but how to display them vertically to where It makes a tile display cluster. I have read this being possible with thr Xdmx program when you use a config file to specify which host is placed on the grid. I kept trying to do this with a simple Xdmx command that refers to a config file and here is the command and the contents of the config file

Code:

command
Xdmx :1 -input LOCALDISPLAY -configfile /path/to/wall.conf

Code:

here is the contents of the wall.conf file
virtual PW 3840x3072 {
   display boba231:0 1280x1024 @0x0;
   display boba211:0 1280x1024 @1280x0;
   display boba121:0 1280x1024 @2560x0;
   display boba141:0 1280x1024 @0x1024;
   display boba131:0 1280x1024 @1280x1024;
   display boba111:0 1280x1024 @2560x1024;
   display boba232:0 1280x1024 @0x2048;
   display boba212:0 1280x1024 @1280x2048;
   display boba122:0 1280x1024 @2560x2048;
}

my problem with this was that whenever it tried to connect to the first screen it would be denied because it couldn't connect to the node (mostly because tcp listening is disabled on the node, I wanted to know how to enable it but all resources in google searches turned up nothing)

in other words, what are the coordinates of the location of the screen on the wall. I don't want the machine I am sitting at to be part of the wall, Instead I want to be the machine running software that controls what is being displayed on each tile.

Here is what I am trying to do
http://seelab.eecs.utk.edu/powerwall/dmx-run.php
http://www.dimin.net/software/bioview/bioview.html

IN the second link scroll all the way to the bottom

Reuti · 08-02-2012, 10:50 AM

But you need an instance to control and synchronize the displays anyway.

Nevertheless, what happens when you want to start an xterm with the above commands?

baronobeefdip · 08-02-2012, 11:32 AM

Quote:

Originally Posted by Reuti

But you need an instance to control and synchronize the displays anyway.

Nevertheless, what happens when you want to start an xterm with the above commands?

After I start getting connections to the displays, What program do I use to control and synchronize the displays, If it has something to do with clustering then Thats a whole other animal, In the first link there was no mention of it being clustered, And the dmx console should have appeared (if the displays were allowing the frontend to connect to it and provided the display's coordinate were entered into the config file correctly the displays should have the images synchronized.) Is the config file that they provided in the configuration page in the first link a valid config file and can it be used to make a display wall?

And I don't think starting xterm is of any use until i can get connected to a screen (unless you just want me to tell you if it displays on the frontend then it does, I get a command prompt with a black background and white text, But I still can't connect to the displays through the network. My frontend's operating systems is Debian Squeeze I am just using FreeBSD as the Backends, The commands above don't work so I can't tell you

Reuti · 08-02-2012, 07:05 PM

Quote:

Originally Posted by baronobeefdip

And I don't think starting xterm is of any use until i can get connected to a screen (unless you just want me to tell you if it displays on the frontend then it does, I get a command prompt with a black background and white text, But I still can't connect to the displays through the network. My frontend's operating systems is Debian Squeeze I am just using FreeBSD as the Backends, The commands above don't work so I can't tell you

No, the xterm should pop up on the remote machine.