[NCLUG] X, xhost, xauth, stuff like that...

[Wayne Schneider]

When you ssh into box B try the command,

ssh -X (box B)

That should allow you to open the application using the display variables from box A.  I have had succes doing exactly what you want to do.

goat
--

On Thu, 13 Sep 2001 22:00:16  
 S. Luke Jones wrote:
>I've been reading the X* howtos and frankly I'm still confused.  Can some
>one (or all of you) who actually understand this stuff check me on this?
>
>I'm sitting in front of a machine, call it A.  If I understand the
>terminology, I'm running an X server and some number of X clients (xterm,
>Netscape, ...) on machine A.  If I look at my $DISPLAY variable it's
>':0.0' meaning the local host display 0 screen 0. So far, so good.
>
>Now, I have another machine B that has a crappy monitor and is in an
>inconvenient place but nonetheless has a lot to recommend it, e.g., it
>has a dialout connection -- and, yes, I could use IP masquerading but
>let's ignore that because I'm talking about X here. Okay, scratch the
>dialout. Say it has a faster CPU (in fact, two CPU's, both of them faster)
>and twice as much RAM.  I'd like to, uh, encode some MP3's and, um, I want
>to use a spiffy graphical MP3 encoding application ("X client", yes?) from
>this machine A with the nice monitor on that machine B with the big iron.
>
>So I open an xterm here on A and ssh over to B.
>
>	luke at A $ ssh B
>	luke at B $ gmp3enc foo.wav
>	Gtk-WARNING **: cannot open display:
>
>OK. Now I need to tell the MP3 encoding client that my actual X server is
>over here.
>
>	luke at B $ export DISPLAY=':0.0'
>	Gtk-WARNING **: cannot open display: :0.0
>
>Oops. That's not here, that's there.
>
>	luke at B $ export DISPLAY='A:0.0'
>	Gtk-WARNING **: cannot open display: A:0.0
>
>Sigh. Assuming that 'A' is resolving correctly -- and at least for "ping"
>it is, not because I understand DNS but because it really isn't that big
>a hassle to maintain two 2-line /etc/hosts files :-) -- then is it fair
>to say that the reason for this most recent error is because the X server
>here on A is rejecting the overtures of B?
>
>Assuming this is true, then I gather what I really don't want to do is
>via "xhost +B" over here on A, because that's a really lame 80's kind of
>insecure solution. Which is fine with me because it doesn't work anyway,
>at least when I did it:
>
>	luke at A $ xhost +B
>	B being added to access control list
>	luke at A $ ssh B
>	luke at B $ gmp3enc foo.wav
>	Gtk-WARNING **: cannot open display: A:0.0
>
>So that leaves me with xauth, and maybe it's just because it's late and
>I'm tired, but I can't make heads or tails of that. The man page, is
>IMHO, impenetrable. I don't even use XDM (or GDM or KDM or whatever). I
>just do an old fashioned startx from, yes -- I'm not afraid to say it
>-- the command line. On the other hand, the kind folks at Red Hat have
>apparently done something with it because I have a .xauth directory
>hierarchy in my $HOME.
>
>Sigh and double-sigh. Bother. Can anyone recommend a HOWTO or other
>material that spells this out in one-syllable words for an old duffer
>like me?
>
>-- 
>Luke Jones = luke/vortex/frii/fullstop/com
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