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+<chapter id="IntroSMB">
+<chapterinfo>
+ &author.dlechnyr;
+ <pubdate>April 14, 2003</pubdate>
+</chapterinfo>
+
+<title>Introduction to Samba</title>
+
+<para><quote>
+"If you understand what you're doing, you're not learning anything."
+-- Anonymous
+</quote></para>
+
+<para>
+Samba is a file and print server for Windows-based clients using TCP/IP as the underlying
+transport protocol. In fact, it can support any SMB/CIFS-enabled client. One of Samba's big
+strengths is that you can use it to blend your mix of Windows and Linux machines together
+without requiring a separate Windows NT/2000/2003 Server. Samba is actively being developed
+by a global team of about 30 active programmers and was originally developed by Andrew Tridgell.
+</para>
+
+<sect1>
+<title>Background</title>
+
+<para>
+Once long ago, there was a buzzword referred to as DCE/RPC. This stood for Distributed
+Computing Environment/Remote Procedure Calls and conceptually was a good idea. It was
+originally developed by Apollo/HP as NCA 1.0 (Network Computing Architecture) and only
+ran over UDP. When there was a need to run it over TCP so that it would be compatible
+with DECnet 3.0, it was redesigned, submitted to The Open Group, and officially became
+known as DCE/RPC. Microsoft came along and decided, rather than pay $20 per seat to
+license this technology, to reimplement DCE/RPC themselves as MSRPC. From this, the
+concept continued in the form of SMB (Server Message Block, or the "what") using the
+NetBIOS (Network Basic Input/Output System, or the "how") compatibility layer. You can
+run SMB (i.e., transport) over several different protocols; many different implementations
+arose as a result, including NBIPX (NetBIOS over IPX, NwLnkNb, or NWNBLink) and NBT
+(NetBIOS over TCP/IP, or NetBT). As the years passed, NBT became the most common form
+of implementation until the advance of "Direct-Hosted TCP" -- the Microsoft marketing
+term for eliminating NetBIOS entirely and running SMB by itself across TCP port 445
+only. As of yet, direct-hosted TCP has yet to catch on.
+</para>
+
+<para>
+Perhaps the best summary of the origins of SMB are voiced in the 1997 article titled, CIFS:
+Common Insecurities Fail Scrutiny:
+</para>
+
+<para><emphasis>
+Several megabytes of NT-security archives, random whitepapers, RFCs, the CIFS spec, the Samba
+stuff, a few MS knowledge-base articles, strings extracted from binaries, and packet dumps have
+been dutifully waded through during the information-gathering stages of this project, and there
+are *still* many missing pieces... While often tedious, at least the way has been generously
+littered with occurrences of clapping hand to forehead and muttering 'crikey, what are they
+thinking?
+</emphasis></para>
+
+</sect1>
+
+<sect1>
+<title>Terminology</title>
+
+<itemizedlist>
+
+ <listitem><para>
+ SMB: Acronym for "Server Message Block". This is Microsoft's file and printer sharing protocol.
+ </para></listitem>
+
+ <listitem><para>
+ CIFS: Acronym for "Common Internet File System". Around 1996, Microsoft apparently
+ decided that SMB needed the word "Internet" in it, so they changed it to CIFS.
+ </para></listitem>
+
+ <listitem><para>
+ Direct-Hosted: A method of providing file/printer sharing services over port 445/tcp
+ only using DNS for name resolution instead of WINS.
+ </para></listitem>
+
+ <listitem><para>
+ IPC: Acronym for "Inter-Process Communication". A method to communicate specific
+ information between programs.
+ </para></listitem>
+
+ <listitem><para>
+ Marshalling: - A method of serializing (i.e., sequential ordering of) variable data
+ suitable for transmission via a network connection or storing in a file. The source
+ data can be re-created using a similar process called unmarshalling.
+ </para></listitem>
+
+ <listitem><para>
+ NetBIOS: Acronym for "Network Basic Input/Output System". This is not a protocol;
+ it is a method of communication across an existing protocol. This is a standard which
+ was originally developed for IBM by Sytek in 1983. To exaggerate the analogy a bit,
+ it can help to think of this in comparison your computer's BIOS -- it controls the
+ essential functions of your input/output hardware -- whereas NetBIOS controls the
+ essential functions of your input/output traffic via the network. Again, this is a bit
+ of an exaggeration but it should help that paradigm shift. What is important to realize
+ is that NetBIOS is a transport standard, not a protocol. Unfortunately, even technically
+ brilliant people tend to interchange NetBIOS with terms like NetBEUI without a second
+ thought; this will cause no end (and no doubt) of confusion.
+ </para></listitem>
+
+ <listitem><para>
+ NetBEUI: Acronym for the "NetBIOS Extended User Interface". Unlike NetBIOS, NetBEUI
+ is a protocol, not a standard. It is also not routable, so traffic on one side of a
+ router will be unable to communicate with the other side. Understanding NetBEUI is
+ not essential to deciphering SMB; however it helps to point out that it is not the
+ same as NetBIOS and to improve your score in trivia at parties. NetBEUI was originally
+ referred to by Microsoft as "NBF", or "The Windows NT NetBEUI Frame protocol driver".
+ It is not often heard from these days.
+ </para></listitem>
+
+ <listitem><para>
+ NBT: Acronym for "NetBIOS over TCP"; also known as "NetBT". Allows the continued use
+ of NetBIOS traffic proxied over TCP/IP. As a result, NetBIOS names are made
+ to IP addresses and NetBIOS name types are conceptually equivalent to TCP/IP ports.
+ This is how file and printer sharing are accomplished in Windows 95/98/ME. They
+ traditionally rely on three ports: NetBIOS Name Service (nbname) via UDP port 137,
+ NetBIOS Datagram Service (nbdatagram) via UDP port 138, and NetBIOS Session Service
+ (nbsession) via TCP port 139. All name resolution is done via WINS, NetBIOS broadcasts,
+ and DNS. NetBIOS over TCP is documented in RFC 1001 (Concepts and methods) and RFC 1002
+ (Detailed specifications).
+ </para></listitem>
+
+ <listitem><para>
+ W2K: Acronym for Windows 2000 Professional or Server
+ </para></listitem>
+
+ <listitem><para>
+ W3K: Acronym for Windows 2003 Server
+ </para></listitem>
+
+</itemizedlist>
+
+<para>If you plan on getting help, make sure to subscribe to the Samba Mailing List (available at
+<ulink url="http://www.samba.org/">http://www.samba.org</ulink>).
+</para>
+
+</sect1>
+
+<sect1>
+<title>Related Projects</title>
+
+<para>
+There are currently two network filesystem client projects for Linux that are directly
+related to Samba: SMBFS and CIFS VFS. These are both available in the Linux kernel itself.
+</para>
+
+<itemizedlist>
+
+ <listitem><para>
+ SMBFS (Server Message Block File System) allows you to mount SMB shares (the protocol
+ that Microsoft Windows and OS/2 Lan Manager use to share files and printers
+ over local networks) and access them just like any other Unix directory. This is useful
+ if you just want to mount such filesystems without being a SMBFS server.
+ </para></listitem>
+
+ <listitem><para>
+ CIFS VFS (Common Internet File System Virtual File System) is the successor to SMBFS, and
+ is being actively developed for the upcoming version of the Linux kernel. The intent of this module
+ is to provide advanced network file system functionality including support for dfs (hierarchical
+ name space), secure per-user session establishment, safe distributed caching (oplock),
+ optional packet signing, Unicode and other internationalization improvements, and optional
+ Winbind (nsswitch) integration.
+ </para></listitem>
+
+</itemizedlist>
+
+<para>
+Again, it's important to note that these are implementations for client filesystems, and have
+nothing to do with acting as a file and print server for SMB/CIFS clients.
+</para>
+
+<para>
+There are other Open Source CIFS client implementations, such as the
+<ulink url="http://jcifs.samba.org/">jCIFS project</ulink>
+which provides an SMB client toolkit written in Java.
+</para>
+
+
+</sect1>
+
+
+<sect1>
+<title>SMB Methodology</title>
+
+<para>
+Traditionally, SMB uses UDP port 137 (NetBIOS name service, or netbios-ns),
+UDP port 138 (NetBIOS datagram service, or netbios-dgm), and TCP port 139 (NetBIOS
+session service, or netbios-ssn). Anyone looking at their network with a good
+packet sniffer will be amazed at the amount of traffic generated by just opening
+up a single file. In general, SMB sessions are established in the following order:
+</para>
+
+<itemizedlist>
+ <listitem><para>
+ "TCP Connection" - establish 3-way handshake (connection) to port 139/tcp
+ or 445/tcp.
+ </para></listitem>
+
+ <listitem><para>
+ "NetBIOS Session Request" - using the following "Calling Names": The local
+ machine's NetBIOS name plus the 16th character 0x00; The server's NetBIOS
+ name plus the 16th character 0x20
+ </para></listitem>
+
+ <listitem><para>
+ "SMB Negotiate Protocol" - determine the protocol dialect to use, which will
+ be one of the following: PC Network Program 1.0 (Core) - share level security
+ mode only; Microsoft Networks 1.03 (Core Plus) - share level security
+ mode only; Lanman1.0 (LAN Manager 1.0) - uses Challenge/Response
+ Authentication; Lanman2.1 (LAN Manager 2.1) - uses Challenge/Response
+ Authentication; NT LM 0.12 (NT LM 0.12) - uses Challenge/Response
+ Authentication
+ </para></listitem>
+
+ <listitem><para>
+ SMB Session Startup. Passwords are encrypted (or not) according to one of
+ the following methods: Null (no encryption); Cleartext (no encryption); LM
+ and NTLM; NTLM; NTLMv2
+ </para></listitem>
+
+ <listitem><para>
+ SMB Tree Connect: Connect to a share name (e.g., \\servername\share); Connect
+ to a service type (e.g., IPC$ named pipe)
+ </para></listitem>
+
+</itemizedlist>
+
+<para>
+A good way to examine this process in depth is to try out
+<ulink url="http://www.securityfriday.com/ToolDownload/SWB/swb_doc.html">SecurityFriday's SWB program</ulink>.
+It allows you to walk through the establishment of a SMB/CIFS session step by step.
+</para>
+
+</sect1>
+
+<sect1>
+<title>Epilogue</title>
+
+<para><quote>
+What's fundamentally wrong is that nobody ever had any taste when they
+did it. Microsoft has been very much into making the user interface look good,
+but internally it's just a complete mess. And even people who program for Microsoft
+and who have had years of experience, just don't know how it works internally.
+Worse, nobody dares change it. Nobody dares to fix bugs because it's such a
+mess that fixing one bug might just break a hundred programs that depend on
+that bug. And Microsoft isn't interested in anyone fixing bugs -- they're interested
+in making money. They don't have anybody who takes pride in Windows 95 as an
+operating system.
+</quote></para>
+
+<para><quote>
+People inside Microsoft know it's a bad operating system and they still
+continue obviously working on it because they want to get the next version out
+because they want to have all these new features to sell more copies of the
+system.
+</quote></para>
+
+<para><quote>
+The problem with that is that over time, when you have this kind of approach,
+and because nobody understands it, because nobody REALLY fixes bugs (other than
+when they're really obvious), the end result is really messy. You can't trust
+it because under certain circumstances it just spontaneously reboots or just
+halts in the middle of something that shouldn't be strange. Normally it works
+fine and then once in a blue moon for some completely unknown reason, it's dead,
+and nobody knows why. Not Microsoft, not the experienced user and certainly
+not the completely clueless user who probably sits there shivering thinking
+"What did I do wrong?" when they didn't do anything wrong at all.
+</quote></para>
+
+<para><quote>
+That's what's really irritating to me."
+</quote></para>
+
+<para>--
+<ulink url="http://hr.uoregon.edu/davidrl/boot.txt">Linus Torvalds, from an interview with BOOT Magazine, Sept 1998</ulink>
+</para>
+
+</sect1>
+
+<sect1>
+<title>Miscellaneous</title>
+
+<!--FIXME: This really needs to go... -->
+
+<para>
+This chapter is Copyright 2003 David Lechnyr (david at lechnyr dot com).
+Permission is granted to copy, distribute and/or modify this document under the terms
+of the GNU Free Documentation License, Version 1.2 or any later version published by the Free
+Software Foundation. A copy of the license is available at http://www.gnu.org/licenses/fdl.txt.
+</para>
+
+</sect1>
+</chapter>