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07.02.03
 By A.P.
Lawrence
Unix and Linux machines have been able to provide Network Neighborhood style file
and print services for some time now, but I constantly see confusion and problems
due to misunderstanding of how these things work.
I'm going to use an example from a real situation involving an XP user and a SCO
Visionfs network. The concepts of this apply to Linux, Mac, Samba: it doesn't
really matter.
The Network
The network consists of Windows 98 and XP machines and Unix/Linux servers. The
major application is client/server accounting application running on the Unix
box. There is a Linux mail server also. File and print services are provided by
Visionfs on the Unix box.
Users need passwords for several functions here:
- Logging in to their Windows desktop
- Accessing the accounting application
- Accessing their POP email
- Accessing shared files on the Unix server
- Using shared printers on the Unix server
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Logins
and Passwords
Most of the machines are Windows 98 and store no data of any importance. These
are set up for normal windows login (no domain controller). Anyone can walk up
to any machine and create a Windows login name, so there is no security. This
is actually deliberate and convenient, as it is often necessary for people to
access the internet or the accounting application while not at their own desk.
Some machines are Windows XP where only the administrator of that machine can
create a login. These machines typically have more sensitive data and are used
by managers. However, as older machines are phased out, XP is the usual replacement,
and a "guest" login is used when the machine needs to have general access.
The accounting application requires a separate login name and password. These
are completely unrelated to any other names or passwords. The accounting administrator
assigns and maintains these.
Email also has its own names and passwords. These are maintained by the email
administrator, though users are allowed to change their own passwords.
Access to files and printers on the Unix box is by Visionfs. There are other utilities
that could do this: Samba and Facetwin
for example. These all have different administration techniques, but the common
point here is that the Windows login name and password is what will determine
access to the files and printers.
The new XP user
A Windows 98 machine was replaced by a new XP box. The user set it up himself,
and successfully installed the accounting application client, and configured his
email. He had access to the internet, the accounting application, and email, but
couldn't access shared files or printers.
The major reason he couldn't do this was because he didn't realize that his Windows
login name was important. On the old Windows 98 box, it had just been "bobf" and
he had a password of "aM2133". When he installed XP, he used the same password,
but spelled out his name as "Bob Franklin". Visionfs has nothing in its database
that knows that "Bob Franklin" is the same as the "bobf" it does know. There is
a way in Visionfs and similar products to map "Bob Franklin" to "bobf", so I did
that, but (not entirely unexpectedly) it still didn't give him access. The problem
has been seen and reported before: http://www.pcunix.com/Bofcusm/1820.html
and http://www.pcunix.com/Bofcusm/1807.html
In this case, the previous name was "Administrator", so I added another mapping
of "Administrator" to "bobf". I also renamed the XP account to "bobf", which meant
that I really didn't need to map "Administrator", but I felt this would just happen
again somewhere down the line, and since all users have the same access permissions
on the Unix box, there's no harm in the mapping.
Incredibly enough, this STILL didn't work. Looking more closely revealed that
the Visionfs password for "bobf" apparently was not "aM2133", so I had to reset
that password (/usr/vision/bin/visionfs password --amend bobf aM2133).
Note that at this point his original Unix login of "bobf" and whatever password
that was is totally unimportant: Visionfs doesn't care, and neither does the accounting
application or the Linux email server. That login is not used for anything at
all. Very often that's where the confusion comes from with programs like Visionfs
or Samba - it is THEIR passwords (matched against the Windows login) that determine
access. While their may or may not be procedures or software in place that keeps
all these passwords consistent, the important thing to understand is that these
products keep their own databases of users and passwords. It is that database
that will be searched to match what the Windows machine sends.
This article appeared at APLawrence.com
Please read this
disclaimer
Copyright and Reprint
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About the Author:
A.P. Lawrence provides SCO Unix and Linux consulting services http://www.pcunix.com
Read this newsletter at: http://www.sysadminnews.com/2003/0702.html |
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