[cvsnt] Question: sspi: connection in workgroup

[keys]

Hi.
My host belongs to a workgroup in a office LAN environment.

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Host info:
 * Windows XP Professional (hostname: TPA22P)
 * keys (Administrators group member on TPA22P)
 * CVSNT2.0.14
 * CVSNTcontrol panel applet settings:
   -Only Impersonation enabled is checked
 * CVSROOT/passwd file not created
 * SystemAuth setting is commented out. (#SystemAuth=Yes)
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Why can I connect to localhost CVSNT server with :sspi: ?
(like below)
Isn't it authenticated by domain?

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C:\home\keys>set CVSROOT=:sspi:TPA22P:/test

C:\home\keys>cvs ls -l -R
Listing modules on server
 :
 :
Directory CVSROOT/Emptydir


C:\home\keys>
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Also, why do I fail to connect like below ?

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C:\home\keys>set CVSROOT=:sspi:keys at TPA22P:/test

C:\home\keys>cvs ls -l -R
cvs [ls aborted]: Authentication protocol rejected access

C:\home\keys>
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Thanks.