On Thu, 25 Jun 2015 at 15:55 -0000, m.roth@xxxxxxxxx wrote:
> I've got a headless server running CentOS 7. I've got a user who
> wants to run some graphical software on it, and view using x
> forwarding. What I don't have clear is how to set this up. I've just
> installed xorg-x11-server-[Xorg, common]. I assume I need to run X,
> but I don't see running this in runlevel 5.
For (ssh based) X forwarding no X server needs to run on the server.
I usually install the xorg-x11-xauth (necessary) and xterm (optional)
rpms on all my servers in case X forwarding becomes necessary.
Then from your desktop (assuming Linux already running X) in a local
xterm do something like:
ssh -Y remote-system
Once logged into the remote system you should now have a DISPLAY
environment variable set which will tell any client applications how
to connect back to the X server on your desktop.
For example, just run xterm on the remote server and a xterm window
will pop up on your display. This is just an example. You could run
xload or any other basic X application.
You can also run more complex applications. Many will run fine.
Other applications may perform poorly (due to the X protocol
chattiness: Firefox, etc). Other applications will have other issues
(some gnome/kde/gtk applications make other assumptions about being on
the same system as the window manager and try to use dbus and local
system things).
Note about -X versus -Y with ssh:
-X enables basic X forwarding, It disables some X functionality making
it "safer" to allow. -X also stops working after about 20 minutes
(this is by design but not well documented). I only recently learned
why it would stop working after pulling out the last of my hair.
-Y allows the full X protocol which might be a security risk. Some
applications will only work with -Y. With this, remote X applications
can grab keyboard interactions, grab passwords, put windows on top of
other windows (obscuring security messages), etc.
For my own choice I use -Y (although I only enable it occasionally to
specific systems).
Stuart
--
I've never been lost; I was once bewildered for three days, but never lost!
-- Daniel Boone
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