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10<H2><A NAME="s3">3. About the CIFS and SMB Protocols</A></H2>
11
12<P>
13<A NAME="CifsSmb"></A> 
14</P>
15
16<H2><A NAME="ss3.1">3.1 What is the Server Message Block (SMB) Protocol?</A></H2>
17
18<P>SMB is a filesharing protocol that has had several maintainers and
19contributors over the years including Xerox, 3Com and most recently
20Microsoft. Names for this protocol include LAN Manager and Microsoft 
21Networking. Parts of the specification has been made public at several 
22versions including in an X/Open document, as listed at 
23<A HREF="ftp://ftp.microsoft.com/developr/drg/CIFS/">ftp://ftp.microsoft.com/developr/drg/CIFS/</A>. No specification
24releases were made between 1992 and 1996, and during that period
25Microsoft became the SMB implementor with the largest market share.
26Microsoft developed the specification further for its products but for
27various reasons connected with developer's workload rather than market
28strategy did not make the changes public. This culminated with the 
29"Windows NT 0.12" version released with NT 3.5 in 1995 which had significant 
30improvements and bugs. Because Microsoft client systems are so popular,
31it is fair to say that what Microsoft with Windows affects all suppliers
32of SMB server products.</P>
33<P>From 1994 Andrew Tridgell began doing some serious work on his 
34Smbserver (now Samba) product and with some helpers started to 
35implement more and more of these protocols. Samba began to take 
36a significant share of the SMB server market.</P>
37
38
39<H2><A NAME="ss3.2">3.2 What is the Common Internet Filesystem (CIFS)?</A></H2>
40
41<P>The initial pressure for Microsoft to document their current SMB
42implementation came from the Samba team, who kept coming across things
43on the wire that Microsoft either didn't know about or hadn't documented
44anywhere (even in the sourcecode to Windows NT.) Then Sun Microsystems
45came out with their WebNFS initiative, designed to replace FTP for file
46transfers on the Internet. There are many drawbacks to WebNFS (including
47its scope - it aims to replace HTTP as well!) but the concept was
48attractive. FTP is not very clever, and why should it be harder to get
49files from across the world than across the room? </P>
50<P>Some hasty revisions were made and an Internet Draft for the Common
51Internet Filesystem (CIFS) was released. Note that CIFS is not an
52Internet standard and is a very long way from becoming one, BUT the
53protocol specification is in the public domain and ongoing discussions
54concerning the spec take place on a public mailing list according to the
55rules of the Internet Engineering Task Force. For more information and
56pointers see 
57<A HREF="http://samba.org/cifs/">http://samba.org/cifs/</A></P>
58<P>The following is taken from 
59<A HREF="http://www.microsoft.com/intdev/cifs/">http://www.microsoft.com/intdev/cifs/</A></P>
60<P>
61<PRE>
62    CIFS defines a standard remote file system access protocol for use
63    over the Internet, enabling groups of users to work together and
64    share documents across the Internet or within their corporate
65    intranets. CIFS is an open, cross-platform technology based on the
66    native file-sharing protocols built into Microsoft� Windows� and
67    other popular PC operating systems, and supported on dozens of
68    other platforms, including UNIX�. With CIFS, millions of computer
69    users can open and share remote files on the Internet without having
70    to install new software or change the way they work.&quot;
71</PRE>
72</P>
73<P>If you consider CIFS as a backwardsly-compatible refinement of SMB that
74will work reasonably efficiently over the Internet you won't be too far
75wrong.</P>
76<P>The net effect is that Microsoft is now documenting large parts of their
77Windows NT fileserver protocols. The security concepts embodied in
78Windows NT are part of the specification, which is why Samba
79documentation often talks in terms of Windows NT. However there is no
80reason why a site shouldn't conduct all its file and printer sharing
81with CIFS and yet have no Microsoft products at all.</P>
82
83
84<H2><A NAME="ss3.3">3.3 What is Browsing? </A></H2>
85
86<P>The term "Browsing" causes a lot of confusion. It is the part of the
87SMB/CIFS protocol which allows for resource discovery. For example, in
88the Windows NT Explorer it is possible to see a "Network Neighbourhood"
89of computers in the same SMB workgroup. Clicking on the name of one of 
90these machines brings up a list of file and printer resources for
91connecting to. In this way you can cruise the network, seeing what
92things are available. How this scales to the Internet is a subject for
93debate. Look at the CIFS list archives to see what the experts think.</P>
94
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