From: "Christian Gelinek" <cgelinek AT radlogic DOT com DOT au>
To: <cygwin AT cygwin DOT com>
Subject: mkgroup: Could not get group info from samba share
Date: Wed, 30 Mar 2011 10:53:01 +1030
Message-ID: <000201cbee70$a154fb00$e3fef100$@com.au>
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Hi everyone!

In my network, I've got a samba server running on a linux machine and I
would like to get the correct user and group names under Cygwin
(CYGWIN_NT-6.1-WOW64 1.7.8(0.236/5/3) 2011-03-01 09:36) under Windows 7
(Windows 7 Professional N Ver 6.1 Build 7600).

Eventually, I found a very helpful forum thread 
(http://omgili.com/mailinglist/cygwin/cygwin/com/001b01ca597832cbb90098632b0
0com.html)
which got me onto the right track for the user names.

If I understood correctly, 
 1. samba takes the user (UID) and group (GID) IDs from the machine it is
running on and somehow generates a Windows SID from that information. 

 2. This information is sent to the windows machine, which then interprets
(or looks up) the correct user and group names as I can see in the Windows
Explorer for the files on my samba drives.

 3. Cygwin doesn't seem to have this remote-lookup-mechanism built-in, so
the /etc/passwd file has to list the Windows SIDs for every user (for the
local machine as well as for the samba machine) and the /etc/group file has
to list the Windows SIDs for every group in order for Cygwin (e.g. the ls -l
command) to report the correct user/group for each file.

The forum thread mentioned earlier suggests to use 

  mkpasswd -U username -S- -L my_samba_box

to get the /etc/passwd entries for the specified user(s) from the samba
server, which worked for me - that means, the user names reported by ls -l
include 'my_samba_box-username' for every file. The group names are still
'????????' (GID=4294967295), which suggests that the Windows SID for the
group reported by samba is not (yet) understood by Cygwin.

So I tried the equivalent command for the groups as suggested by the
aforementioned forum thread:

  mkgroup -U username -S- -L my_samba_box

Here, I was out of luck as this command did not return anything. I also
tried

  mkgroup -U username -S- -D my_samba_box

but that reported 'mkgroup (102): [1355] The specified domain either does
not exist or could not be contacted'.

Any help on how to get the group-SID-mapping from the samba server so I can
add that information to my /etc/group file would be highly appreciated.

Thanks,
Christian


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