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I followed cygwin user guide as below:

on windows xp, i started Cygwin/X->XWin server,

ssh -Y user@ip

i saw below warning

Warning: No xauth data; using fake authentication data for X11 forwarding.

after login, i typed bash-3.00$ xclock & [1] 26962 bash-3.00$ Xlib: connection to "clientip:0.0" refused by server Xlib: No protocol specified

Error: Can't open display: clientip:0.0

can anyone help?

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Is "clientip" the Cygwin machine or the other one? (I have to ask because people sometimes get confused about the words "client" and "server" with X, thinking that the machine on their desk can't be the "server" - it is!) – Alan Curry Jul 30 '12 at 5:49
the ""clientip:0.0" i'm referring to the windows xp machine where i install my cygwin and xserver software. – hetaoblog Jul 30 '12 at 6:17
Can you run "xauth list" locally on the Cygwin machine? – Alan Curry Jul 30 '12 at 6:49
i run the command but got nothing – hetaoblog Jul 30 '12 at 6:59
what command line did you use to start Cygwin/X? – Alan Curry Jul 30 '12 at 7:02
up vote 2 down vote accepted

In a chat session some more evidence was examined, and this conclusion was reached:

yes, sometime ago, i added export DISPLAY=mywindowsip:0.0 in my shell rc file
so this was executed everytime when i ssh to the shell

The ssh-forwarded DISPLAY variable was being obliterated, and the unix machine was making unauthorized connections directly to the cygwin X server.

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