Providing the X server is allowing TCP domain connections and accepts
the MIT-MAGIC-COOKIE-1 over TCP connections, getting the MIT-MAGIC-
COOKIE-1 to the remote host is relatively easy.  The xauth on the
console host can see the MIT-MAGIC-COOKIE-1 and can be used to copy it
into the .Xauthority file in the users home directory.  Thereafter
remote applications will automatically pick it up from the user's (NFS
shared) home directory on any other hosts they need to use.

We have seen many of our applications where the overhead of the
encryption is simply massive and combined with the latency of the
continuous context switching to the SSH process to encrypt the data
becomes utterly unacceptable.  Granted one particular application
involves synchronising video feeds from multiple video camera captures
performed by multiple hosts but in this and other roles X11 is up to the
task; tunnelled/encrypted X11 is far too slow and is not suitable for
purpose.

Regards, Bevis.

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You received this bug notification because you are a member of Desktop
Packages, which is subscribed to lightdm in Ubuntu.
https://bugs.launchpad.net/bugs/1206533

Title:
  X server authority only allows local connections even if xserver-
  allow-tcp=true

Status in Light Display Manager:
  Triaged
Status in “lightdm” package in Ubuntu:
  Triaged

Bug description:
  I'm currently working on configuring Ubuntu 12.04 Linux to match our
  user environment - one of the aspects I'm working on is enabling X11
  over TCP as we have a large number of graphical applications running
  on local (same-subnet) compute server systems.  Encrypting the X11
  stream between clients and servers on the same physical network switch
  inside a secured floor of offices seems like insanity to me.

  I've obviously configured Lightdm to start the Xorg X11 server with
  TCP mode connections enabled, but the -auth argument (which I assume
  is provided by lightdm) points to a file called
  /var/run/lightdm/root/:0.  Despite the TCP mode connection being
  enabled, the only MIT-MAGIC-COOKIE-1 key that is placed within this
  file includes the "hostname/unix:0" specification which limits it's
  use to Unix domain sockets only.

  What I need to do is to have lightdm (assuming it is lightdm that is
  creating this authorisation file) create it with simply "hostname:0"
  so that the MIT-MAGIC-COOKIE-1 key may be used on X11 over TCP
  connections as well as those over X11 over Unix Domain socket
  connections.

  I have confirmed that extracting the key from the :0 file using Xauth
  -f :0 list followed by a correspondingly altered re-insertion of the
  key without the /unix part using Xauth -f :0 add ... command does
  indeed work.

  My first question is whether there is something I've missed in the
  lightdm configuration file that would allow me to specify that I want
  the MIT-MAGIC-COOKIE-1 enabled for both TCP and Unix domain
  connections?

  The second point which follows on from that is whether when allowing
  TCP connections to the Xserver, maybe lightdm SHOULD remove the /unix
  element from the MIT_MAGIC-COOKIE-1 stored in the :0 file.  It would
  seem to me to be logical that it should.

  And the final point is seeking advice on the best recommended way to
  work around this problem for the time being.  I assume I could do the
  xauth list/xauth add steps within the display-setup-script if
  necessary.  Is this the best place to do it?

  Thanks in advance for your help.

  Description:  Ubuntu 12.04.2 LTS
  Release:      12.04

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: lightdm 1.2.3-0ubuntu2.3
  ProcVersionSignature: Ubuntu 3.2.0-49.75-generic 3.2.46
  Uname: Linux 3.2.0-49-generic x86_64
  NonfreeKernelModules: nvidia
  ApportVersion: 2.0.1-0ubuntu17.3
  Architecture: amd64
  Date: Tue Jul 30 15:16:52 2013
  MarkForUpload: True
  ProcEnviron:
   LANGUAGE=en_GB:
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_GB.UTF-8
   SHELL=/bin/csh
  SourcePackage: lightdm
  UpgradeStatus: No upgrade log present (probably fresh install)

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