Solution to: -clipboard does not work when using XDMCP connection.

[Chris Capon]

This e-mail is for documentation purposes, no further help is needed.


With the default Cygwin/X install, the XWin.exe -clipboard option does 
not seem to work when connecting using the XDMCP protocol to a Linux 
server running GDM.

The unix and Windows clipboards would not synchronized and copy/paste 
did not work across sessions.

In /var/log/XWin.0.log, these messages were displayed:

-------------------------
winInitClipboard ()
winProcQueryTree - winInitClipboard returned.
winClipboardProc - Hello
DetectUnicodeSupport - Windows NT/2000/XP
winClipboardProc - DISPLAY=127.0.0.1:0.0
AUDIT: Fri Mar  6 13:23:07 2009: 4144 XWin: client 4 rejected from IP 
127.0.0.1
winProcEstablishConnection - ProcEstablishConnection failed, bailing.
winClipboardProc - Could not open display, try: 1, sleeping: 4
AUDIT: Fri Mar  6 13:23:11 2009: 4144 XWin: client 4 rejected from IP 
127.0.0.1
winClipboardProc - Could not open display, try: 2, sleeping: 4
AUDIT: Fri Mar  6 13:23:15 2009: 4144 XWin: client 4 rejected from IP 
127.0.0.1
winClipboardProc - Could not open display, try: 3, sleeping: 4
-------------------------

My launch batch file for XWin.exe is fairly simple:

    @echo off
    start "Title"  C:\cygwin\bin\XWin.exe -clipboard -query 192.168.0.1


I tried a number of solutions offered by others, but this one solved the 
problem.

Create a text file in your Cygwin installation folder called:

    /etc/X0.hosts       (that's X-zero dot hosts)

It should contain one line:

    localhost

Effectively, this permissions file allows the X server to access your 
Windows machine's local IP address (127.0.0.1).

This file should probably be part of the standard Cygwin/X install.  It 
also doesn't seem to be mentioned in the Cygwin/X documentation (maybe 
its there and I just missed it).


Now the log file reports:
-------------------------
winClipboardProc - Hello
DetectUnicodeSupport - Windows NT/2000/XP
winClipboardProc - DISPLAY=127.0.0.1:0.0
winProcEstablishConnection - Clipboard client already launched, returning.
winClipboardProc - XOpenDisplay () returned and successfully opened the 
display.
-------------------------

and the clipboard now works properly.  Copy and Paste between windows 
and X works as expected.


For GDM users, you may also need to set an entry in your gdm config file 
located at:

    /etc/gdm/gdm.conf

In the [daemon] section:

    [daemon]
    KillInitClients=false

I haven't confirm the GDM requirement but this is how it's set up in my 
configuration.

Hope this helps someone.
Chris.


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