xterm Xt error: Can't open display

[Bit Twister]

Hi All,
My workstation runs RedHat. When I SSH (or Telnet) to remote host and
set the DISPLAY variable, and run, xterm (for example), I get the error
message "xterm Xt error: Can't open display:". Where could be the problem?

I assume you did a
xhost +some_node before the ssh

Normally when you "ssh -X some_node" the DISPLAY env should be already
set. Should look like some_node:nn not :0

The ssh service (sshd) on some_node may not allow the display to be
sent back or the firewalls on either machine may have ports blocked.

Of course you checked the messages logs on each machine. :)

[Ahmed Moustafa]

Post by Bit Twister

Hi All,
My workstation runs RedHat. When I SSH (or Telnet) to remote host and
set the DISPLAY variable, and run, xterm (for example), I get the error
message "xterm Xt error: Can't open display:". Where could be the problem?

I assume you did a
xhost +some_node before the ssh
Normally when you "ssh -X some_node" the DISPLAY env should be already
set. Should look like some_node:nn not :0
The ssh service (sshd) on some_node may not allow the display to be
sent back or the firewalls on either machine may have ports blocked.

I think that is what is happening, the ports are blocked somewhere, and
very possibly it is my machine but I don't know how to allow it.

Post by Bit Twister
Of course you checked the messages logs on each machine. :)

[Bit Twister]

Post by Ahmed Moustafa

Post by Bit Twister
The ssh service (sshd) on some_node may not allow the display to be
sent back or the firewalls on either machine may have ports blocked.

I think that is what is happening, the ports are blocked somewhere, and
very possibly it is my machine but I don't know how to allow it.

Guessing tcp 6000:6020 are blocked.

Anything look promising with
grep DPT= /var/log/messages

Post by Ahmed Moustafa

Post by Bit Twister
Of course you checked the messages logs on each machine. :)

[Ahmed Moustafa]

Post by Bit Twister

Post by Ahmed Moustafa

Post by Bit Twister
The ssh service (sshd) on some_node may not allow the display to be
sent back or the firewalls on either machine may have ports blocked.

I think that is what is happening, the ports are blocked somewhere, and
very possibly it is my machine but I don't know how to allow it.

Guessing tcp 6000:6020 are blocked.
Anything look promising with
grep DPT= /var/log/messages

Nothing at all.

Post by Bit Twister

Post by Ahmed Moustafa

Post by Bit Twister
Of course you checked the messages logs on each machine. :)

[CL [dnoyeB] Gilbert]

Could you explain what is happening here? How can I do this?

xhost +some_node allows connections to the X server on the from_node.
ssh -X some_node creates an encrypted communication login connection
to some_node. The -X enables X forwarding from some_node.
That assumes the XForwarding is enabled on some_node.

will this allow me to stop using VNC??

I give up, can you?

Be serious. VNC is allowing me to connect from a remote location to my
Linux box. Will this X stuff allow me to do that?

CL

[Bit Twister]

So this is from one box with X to another. Like I can run an X session on
my laptop thats actually connected to my desktop?

Yes.

Can I do this from windows?

If you mean Microsoft, yes.

VNC is working and gives me a remote GUI on windows thats connected to my
Linux box. Just wondering if their is a simpler cleaner way, maybe thats
not as slow as VNC!?

Such questions with mushy values. I have not used VNC.

My company did provide me with a third party VPN which required a
secure key card to generate a numeric key to gain access through
their network to connect to work.

I loaded the cygwin sofware which makes Windows look like linux. I
used it's X server to display apps from work. I also used it a work in
place of eXceed at work.

Very intense X applications, Oracle Forms, would be a little slower
than work. I may have had some performance gain because the VPN was
compressing the data stream and since I was running ssh at work and
home the encripted data made the links to appear about the same speed.

Here again it depended on the X applications that you run. Just using
xterms, emacs, edt on a vax, not that much of a load. Trying to bring
a Solaris desktop back on my cable modem was slooow starting up.

I think putty might be a small fast X server for your use. I have
not used it. cygwin is a big download just for an X server.


Today's Tip of the Day, very large
Frequently Asked Questions (faq) Search engine:

http://groups.google.com/advanced_group_search
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*linux* in the Newsgroup, pick English

[CL [dnoyeB] Gilbert]

Thanks for the info. I do use putty, but its ssh only, it deos not do X
or anything else.

I'll have to test that one day. perhaps with cygwin.


CL

[Vincent Zweije]

In article <X8V0b.1517$***@newsread3.news.pas.earthlink.net>, Ahmed
Moustafa <***@NOSPAMarbornet.org> wrote:

|| My workstation runs RedHat. When I SSH (or Telnet) to remote host and
|| set the DISPLAY variable, and run, xterm (for example), I get the error
|| message "xterm Xt error: Can't open display:". Where could be the problem?

(1) Either:
(a) You forgot to export DISPLAY from a bourne shell clone,
or:
(b) You should have used setenv, not set, from a csh clone.

All this doesn't matter anyway, because:

(2) You should have supplied +X to your ssh command, which enables
X11 forwarding. The remote sshd sets DISPLAY for you; don't do
that manually.

By the way, using xhost (as someone mentioned) with ssh is a contradiction
in terms.

Have a look at the Remote X Apps mini-HOWTO. It'll clarify some stuff
for you.

Ciao. Vincent.