Re: Xsecurity - how do I turn on MIT-MAGIC-COOKIE-1 and .Xauthority support?

2008-02-05 Thread Noam Meltzer
Ira,

Have you tried the FreeNX project? It gives superior performance over VNC
  supports multi-sessions and/or multi-users. (which VNC does not)

It is linked with the standard X libraries on your system (X.org in RHEL4/5
case) so I suspect it should provide all the X extensions you require.

- Noam

2008/2/3 Ira Abramov [EMAIL PROTECTED]:

   On Feb 3, 2008 11:15 AM, Shachar Shemesh [EMAIL PROTECTED]
   wrote:
  
VNC on Windows behaves differently than on Linux. On Linux, it
opens its own unique X server, and then exports its display using
the VNC protocol. On Windows, VNC server exports the main Windows
display.

 their client is a windows machine, then an unimaginately-named linux
 machine xserver runs Xvnc for 12 users, and from there they dispatch
 jobs to a cluster of CPU machines via a dispatcher whose name I forgot.
 The target machines already mount the same homedirs, so of course I have
 the MIT and XDM cookies in the .Xauthority at the far end as well. The
 problem is an interactive job tries to spawn at the target node but Xvnc
 ignores the xauth mechanism and blocks the client (and as I said - xhost
 + works but is too permissive)

 They just moved to that VNC setup because they are trying to stop using
 a local Xserver on the windows. they are surprised to discover vnc is
 slower, even though I explain the plusses and minuses.

 The local server is a commercial one, I was told they triend the local X
 from Cygwin with bad results but never gave me a full explanation.
 I'll have to either test the current cygwin-xorg and see if it's better
 for thזm, or test their propriatery/commercial Xserver-for-windows for
 any sort of MIT cookie support.

 Quoting Ilya Konstantinov, from the post of Sun, 03 Feb:
   Nowadays, you have VNC servers which act as X11 clients and export
   whatever X11 display you point them at. Those are the VNC servers
   which come with GNOME and KDE as their remote desktop offerings.

 I'm not going to run 12 full xorgs on the machine. Xvnc does the correct
 job, just misses support for some of the security models (supports only
 xhost, basically)

  See also the discussion there about using x11vnc from inetd for spawning
 new
  X sessions on demand in response to VNC connections.

 that means I lose sessions on disconnect, AS WELL as get sluggy GUI
 reactions. that's less useful than a local Xsserver on the windows.

 --
 Target of opportunity
 Ira Abramov
 http://ira.abramov.org/email/

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Re: Xsecurity - how do I turn on MIT-MAGIC-COOKIE-1 and .Xauthority support?

2008-02-03 Thread Ira Abramov
Quoting Shachar Shemesh, from the post of Sun, 03 Feb:
 Ira Abramov wrote:

 is the RHEL-supplied Xvnc ignoring MIT-MAGIC-COOKIE because of
 configuration, or something missing at compile time?
 I believe they ignore it because their X server doesn't support it.

damn... I suspected that was it :-(

Time to go test their local windows Xserver and see what it DOES
support.

-- 
It's all good
Ira Abramov
http://ira.abramov.org/email/

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Re: Xsecurity - how do I turn on MIT-MAGIC-COOKIE-1 and .Xauthority support?

2008-02-03 Thread Shachar Shemesh

Ira Abramov wrote:



Time to go test their local windows Xserver and see what it DOES
support.
  
VNC on Windows behaves differently than on Linux. On Linux, it opens its 
own unique X server, and then exports its display using the VNC 
protocol. On Windows, VNC server exports the main Windows display. This 
means that if you want to export X11 programs running on Windows using 
VNC, you also have to explicitly run an X11 server.


Which is good news. Cygwin has a Windows port of X.org, which, as you 
know, does support MIT cookies. Problem solved.


Shachar


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Re: Xsecurity - how do I turn on MIT-MAGIC-COOKIE-1 and .Xauthority support?

2008-02-03 Thread Ilya Konstantinov
On Feb 3, 2008 11:15 AM, Shachar Shemesh [EMAIL PROTECTED] wrote:

 VNC on Windows behaves differently than on Linux. On Linux, it opens its
 own unique X server, and then exports its display using the VNC
 protocol. On Windows, VNC server exports the main Windows display.


Nowadays, you have VNC servers which act as X11 clients and export whatever
X11 display you point them at. Those are the VNC servers which come with
GNOME and KDE as their remote desktop offerings.

Here's one:
http://www.karlrunge.com/x11vnc/

BTW, those kind of VNC servers only became possible (with reasonable
performance) with the introduction of the DAMAGE extension, so they pretty
much have to run on a modern X server - or otherwise there'll be very
CPU-intensive screen polling.


Re: Xsecurity - how do I turn on MIT-MAGIC-COOKIE-1 and .Xauthority support?

2008-02-03 Thread Ilya Konstantinov
On Feb 3, 2008 12:49 PM, Ilya Konstantinov [EMAIL PROTECTED]
wrote:

 On Feb 3, 2008 11:15 AM, Shachar Shemesh [EMAIL PROTECTED] wrote:

  VNC on Windows behaves differently than on Linux. On Linux, it opens its
  own unique X server, and then exports its display using the VNC
  protocol. On Windows, VNC server exports the main Windows display.


 Nowadays, you have VNC servers which act as X11 clients and export
 whatever X11 display you point them at. Those are the VNC servers which come
 with GNOME and KDE as their remote desktop offerings.

 Here's one:
 http://www.karlrunge.com/x11vnc/

 BTW, those kind of VNC servers only became possible (with reasonable
 performance) with the introduction of the DAMAGE extension, so they pretty
 much have to run on a modern X server - or otherwise there'll be very
 CPU-intensive screen polling.


This describes a configuration more like Xvnc:
http://www.karlrunge.com/x11vnc/#faq-xvfb

See also the discussion there about using x11vnc from inetd for spawning new
X sessions on demand in response to VNC connections.


Re: Xsecurity - how do I turn on MIT-MAGIC-COOKIE-1 and .Xauthority support?

2008-02-03 Thread Ira Abramov
  On Feb 3, 2008 11:15 AM, Shachar Shemesh [EMAIL PROTECTED]
  wrote:
 
   VNC on Windows behaves differently than on Linux. On Linux, it
   opens its own unique X server, and then exports its display using
   the VNC protocol. On Windows, VNC server exports the main Windows
   display.

their client is a windows machine, then an unimaginately-named linux
machine xserver runs Xvnc for 12 users, and from there they dispatch
jobs to a cluster of CPU machines via a dispatcher whose name I forgot.
The target machines already mount the same homedirs, so of course I have
the MIT and XDM cookies in the .Xauthority at the far end as well. The
problem is an interactive job tries to spawn at the target node but Xvnc
ignores the xauth mechanism and blocks the client (and as I said - xhost
+ works but is too permissive)

They just moved to that VNC setup because they are trying to stop using
a local Xserver on the windows. they are surprised to discover vnc is
slower, even though I explain the plusses and minuses.

The local server is a commercial one, I was told they triend the local X
from Cygwin with bad results but never gave me a full explanation.
I'll have to either test the current cygwin-xorg and see if it's better
for thזm, or test their propriatery/commercial Xserver-for-windows for
any sort of MIT cookie support.

Quoting Ilya Konstantinov, from the post of Sun, 03 Feb:
  Nowadays, you have VNC servers which act as X11 clients and export
  whatever X11 display you point them at. Those are the VNC servers
  which come with GNOME and KDE as their remote desktop offerings.

I'm not going to run 12 full xorgs on the machine. Xvnc does the correct
job, just misses support for some of the security models (supports only
xhost, basically)

 See also the discussion there about using x11vnc from inetd for spawning new
 X sessions on demand in response to VNC connections.

that means I lose sessions on disconnect, AS WELL as get sluggy GUI
reactions. that's less useful than a local Xsserver on the windows.

-- 
Target of opportunity
Ira Abramov
http://ira.abramov.org/email/

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Xsecurity - how do I turn on MIT-MAGIC-COOKIE-1 and .Xauthority support?

2008-02-02 Thread Ira Abramov
howdie gang!

I have two clients with a similar problem: the run a job dispatcher that
sends their requests to a free node in a compute cluster to run a
compilation or simulation of the system. Some of those jobs are supposed
to open an interactive X connection. the display is set right but of
course one needs authority to access the user's display. right now it
means the user has to run it with xhost + and that's just too
permissive.

The users run with vnc clients to Xvnc servers, that don't seem to
support secure-RPC either, so looks like xhost +nis:[EMAIL PROTECTED] can't
work either.

is the RHEL-supplied Xvnc ignoring MIT-MAGIC-COOKIE because of
configuration, or something missing at compile time? the Xsecurity
manpage is not giving too many hints...

Thanks,
Ira.

-- 
All your base are belong to us
Ira Abramov
http://ira.abramov.org/email/

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Re: Xsecurity - how do I turn on MIT-MAGIC-COOKIE-1 and .Xauthority support?

2008-02-02 Thread Amos Shapira
On Feb 2, 2008 11:49 PM, Ira Abramov [EMAIL PROTECTED] wrote:

 howdie gang!

 I have two clients with a similar problem: the run a job dispatcher that
 sends their requests to a free node in a compute cluster to run a
 compilation or simulation of the system. Some of those jobs are supposed
 to open an interactive X connection. the display is set right but of
 course one needs authority to access the user's display. right now it
 means the user has to run it with xhost + and that's just too
 permissive.


How about copying over the cookie using xauth nextract ... | ssh ... xauth
nmerge ... (or whatever is required to pass over the cookie, you get the
idea)?

Also try setting up the XAUTHORITY envariable to point to a .Xauthority file
with the right cookies in it.

--Amos


Re: Xsecurity - how do I turn on MIT-MAGIC-COOKIE-1 and .Xauthority support?

2008-02-02 Thread Shachar Shemesh

Ira Abramov wrote:


is the RHEL-supplied Xvnc ignoring MIT-MAGIC-COOKIE because of
configuration, or something missing at compile time?

I believe they ignore it because their X server doesn't support it.

A VNC server is also an X server, which means that you are NOT using a 
X.org or XFree86 based server. If the server does not support an 
extension, then nothing you will do with the files will make it.


Shachar

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