X11Forward and xauth problems

[Jon TURNEY]

On 23/03/2015 20:48, Andrew DeFaria wrote:
> Normally I just turn on -X (or put X11Forward yes in ~/.ssh/config) but
> that usually results in a noticeable delay in logging in and the
> following error:
>
> Warning: untrusted X11 forwarding setup failed: xauth key data not
> generated
> Warning: No xauth data; using fake authentication data for X11 forwarding.

Firstly, if you don't want these warnings, use ssh -Y.

(By using ssh -X, you are asking for something which the X server can't 
give you, hence the warnings.  See 
http://x.cygwin.com/docs/faq/cygwin-x-faq.html#q-trusted-untrusted-x11-forwarding 
for more details)

> /usr/bin/xauth:  unable to link authority file
> /home/adefaria/.Xauthority, use /home/adefaria/.Xauthority-n
> Cm-app-ldev01:
>
> I've asked about this in the past and I think the answer was that the
> message was correct but you shouldn't worry about it. If it didn't slow

I'm sorry, I only have a vague memory of this discussion.

> me down I probably would just ignore it. But it slows me down. So I ssh
> instead without X11Forward turned on then, when I need to run an X
> client, I do export DISPLAY=adefaria-lt:0 and make sure that I did an
> xhost + there at least once. But now that's broken!
>
> Adefaria-lt:xhost +
> access control disabled, clients can connect from any host
> Adefaria-lt:ssh cm-app-ldev01
> Cm-app-ldev01:export DISPLAY=adefaria-lt:0
> Cm-app-ldev01:xclock
> Error: Can't open display: adefaria-lt:0
> Cm-app-ldev01:

If you want this to work, you will now (since X server 1.17) need to 
start the server with the option '-listen tcp'.

[1] https://cygwin.com/ml/cygwin-xfree-announce/2015-02/msg00026.html
[2] 
http://x.cygwin.com/docs/ug/using-remote-apps.html#using-remote-apps-telnet
[3] 
http://x.cygwin.com/docs/faq/cygwin-x-faq.html#q-remote-clients-cant-connect
[4] https://cygwin.com/ml/cygwin-xfree/2015-02/msg00051.html

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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