X11 forwarding request failed on channel 0

X11 forwarding request failed on channel 0

[Haanraadts, Mark (HBO) via cygwin]

I have a problem with remote ssh sessions to corporate Red Hat 6 servers and X11 forwarding. Xclock works perfectly fine on my local CYGWIn install. On a remote server I get:
$ xclock
Error: Can't open display:

Here's the debug shell logfile:

debug2: we sent a password packet, wait for reply
debug1: Authentication succeeded (password).
Authenticated to <host>.
debug1: channel 0: new [client-session]
debug2: channel 0: send open
debug1: Requesting mailto:no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: pledge: exec
debug2: channel_input_open_confirmation: channel 0: callback start
debug2: x11_get_proto: /usr/bin/xauth  list :0.0 2>/dev/null
debug1: Requesting X11 forwarding with authentication spoofing.
debug2: channel 0: request x11-req confirm 1
debug2: fd 3 setting TCP_NODELAY
debug2: client_session2_setup: id 0
debug2: channel 0: request pty-req confirm 1
debug2: channel 0: request shell confirm 1
debug2: channel_input_open_confirmation: channel 0: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug2: channel_input_status_confirm: type 100 id 0
X11 forwarding request failed on channel 0
debug2: channel_input_status_confirm: type 99 id 0
debug2: PTY allocation request accepted on channel 0
debug2: channel 0: rcvd adjust 2097152
debug2: channel_input_status_confirm: type 99 id 0
debug2: shell request accepted on channel 0
Last login: Wed Sep 11 17:01:50 2019 from 10.218.16.112

Did a lot of Googling and I already changed this in /etc/ssh/sshd_config
X11Forwarding yes
AddressFamily inet
X11UseLocalhost no

Here's how I'm starting X-Windows
startxwin &
sleep 10
export DISPLAY=:0.0
xhost +
xterm -sb -sl 5000 -geometry 168x17+380+0 -T "XTERM 1" &
xterm -sb -sl 5000 -geometry 168x17+380+315 -T "XTERM 2" &
xterm -sb -sl 5000 -geometry 168x16+380+600 -T "XTERM 3" &



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Re: X11 forwarding request failed on channel 0

[Brian Inglis]

On 2019-09-12 07:37, Haanraadts, Mark (HBO) via cygwin wrote:
> I have a problem with remote ssh sessions to corporate Red Hat 6 servers and X11 forwarding. Xclock works perfectly fine on my local CYGWIn install. On a remote server I get:
> $ xclock
> Error: Can't open display:
> 
> Here's the debug shell logfile:
> 
> debug2: we sent a password packet, wait for reply
> debug1: Authentication succeeded (password).
> Authenticated to <host>.
> debug1: channel 0: new [client-session]
> debug2: channel 0: send open
> debug1: Requesting mailto:no-more-sessions@openssh.com
> debug1: Entering interactive session.
> debug1: pledge: exec
> debug2: channel_input_open_confirmation: channel 0: callback start
> debug2: x11_get_proto: /usr/bin/xauth  list :0.0 2>/dev/null
> debug1: Requesting X11 forwarding with authentication spoofing.
> debug2: channel 0: request x11-req confirm 1
> debug2: fd 3 setting TCP_NODELAY
> debug2: client_session2_setup: id 0
> debug2: channel 0: request pty-req confirm 1
> debug2: channel 0: request shell confirm 1
> debug2: channel_input_open_confirmation: channel 0: callback done
> debug2: channel 0: open confirm rwindow 0 rmax 32768
> debug2: channel_input_status_confirm: type 100 id 0
> X11 forwarding request failed on channel 0
> debug2: channel_input_status_confirm: type 99 id 0
> debug2: PTY allocation request accepted on channel 0
> debug2: channel 0: rcvd adjust 2097152
> debug2: channel_input_status_confirm: type 99 id 0
> debug2: shell request accepted on channel 0
> Last login: Wed Sep 11 17:01:50 2019 from 10.218.16.112
> 
> Did a lot of Googling and I already changed this in /etc/ssh/sshd_config
> X11Forwarding yes
> AddressFamily inet
> X11UseLocalhost no
> 
> Here's how I'm starting X-Windows
> startxwin &
> sleep 10
> export DISPLAY=:0.0
> xhost +
> xterm -sb -sl 5000 -geometry 168x17+380+0 -T "XTERM 1" &
> xterm -sb -sl 5000 -geometry 168x17+380+315 -T "XTERM 2" &
> xterm -sb -sl 5000 -geometry 168x16+380+600 -T "XTERM 3" &

The Cygwin/X shortcut starts X window server with:

	run --quote /bin/sh -l -c "cd; exec /usr/bin/startxwin"

You should not manually set DISPLAY - that is set by the X server - you should
start clients from ~/.Xclients, or manually from your X desktop applications menu.

DISPLAY=:0 or DISPLAY=:0.0 are only useful on implied localhost; you either have
to use X11 forwarding:
- on the command line ssh -X | -Y, or
- enable that in ~/.ssh/config on a Host connection:

	ForwardX11 yes
	ForwardX11Trusted yes

- note that untrusted client sessions are terminated after 20 minutes, or as per
policy, and data returned may be zeroed or access attempts result in an error;

if not using ssh forwarding, the DISPLAY value must be prefixed with a host name
resolvable on the remote host to your local host.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

This email may be disturbing to some readers as it contains
too much technical detail. Reader discretion is advised.

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Re: X11 forwarding request failed on channel 0

[Andrew DeFaria]

On 06/18/2013 04:01 PM, Jon TURNEY wrote:
> On 18/06/2013 17:23, Andrew DeFaria wrote:
>> Lately I noticed the following error when attempting to ssh from my Ubuntu
> Not sure if "lately" means you haven't changed anything, but it didn't report
> this error before, or you've only recently started paying attention :D
More like the later. I only run Windows in a VM anymore and I only 
really use it for Playon (See http://playon.tv) - that and I have some 
Perl code I want to make sure works on Windows through Cygwin. So most 
of the time I'm not running any X stuff on Cygwin.
>> (13.04) systems to my Cygwin system with X11 Forwarding turned on:
>>
>> X11 forwarding request failed on channel 0
>>
>> Any idea of how I can fix this?
>>
>> Not sure if this is a Cygwin issue (but it does involve ssh) or a Cygwin/X issue.
> Possibly you do not have the remote sshd configured to allow X11 forwarding.
>
> See A5 to Q6.1 in the Cygwin/X FAQ [1].  The other answers may also be
> informative.
>
> [1] http://x.cygwin.com/docs/faq/cygwin-x-faq.html#q-ssh-no-x11forwarding
That seems to be it - ForwardX11 was commented out in /etc/sshd_config 
on the Cygwin box. Is this a new default?

In any event thanks.
-- 
Andrew DeFaria <http://defaria.com>
It has been said that democracy is the worst form of government except 
all the others that have been tried.


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Re: X11 forwarding request failed on channel 0

[Jon TURNEY]

On 18/06/2013 17:23, Andrew DeFaria wrote:
> Lately I noticed the following error when attempting to ssh from my Ubuntu

Not sure if "lately" means you haven't changed anything, but it didn't report
this error before, or you've only recently started paying attention :D

> (13.04) systems to my Cygwin system with X11 Forwarding turned on:
> 
> X11 forwarding request failed on channel 0
> 
> Any idea of how I can fix this?
> 
> Not sure if this is a Cygwin issue (but it does involve ssh) or a Cygwin/X issue.

Possibly you do not have the remote sshd configured to allow X11 forwarding.

See A5 to Q6.1 in the Cygwin/X FAQ [1].  The other answers may also be
informative.

[1] http://x.cygwin.com/docs/faq/cygwin-x-faq.html#q-ssh-no-x11forwarding

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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X11 forwarding request failed on channel 0

[Andrew DeFaria]

Lately I noticed the following error when attempting to ssh from my 
Ubuntu (13.04) systems to my Cygwin system with X11 Forwarding turned on:

X11 forwarding request failed on channel 0

Any idea of how I can fix this?

Not sure if this is a Cygwin issue (but it does involve ssh) or a 
Cygwin/X issue.
-- 
Andrew DeFaria <http://defaria.com>
If you knees bent the other way, what would chairs look like?


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