Chapter 1: Learning the Samba

1. Learning the Samba

Contents:
What is Samba
What Can Samba Do For Me?
Getting Familiar with a SMB/CIFS Network
Microsoft Implementations
An Overview of the Samba Distribution
How Can I Get Samba?
What's New in Samba 2.0?
And That's Not All...

If you are a typical system administrator, then you know what it means to be swamped with work. Your daily routine is filled with endless hardware incompatibility issues, system outages, data backup problems, and a steady stream of angry users. So adding another program to the mix of tools that you have to maintain may sound a bit perplexing. However, if you're determined to reduce the complexity of your work environment, as well as the workload of keeping it running smoothly, Samba may be the tool you've been waiting for.

A case in point: one of the authors of this book used to look after 70 Unix developers sharing 5 Unix servers. His neighbor administered 20 Windows 3.1 users and 5 OS/2 and Windows NT servers. To put it mildly, the Windows 3.1 administrator was swamped. When he finally left -- and the domain controller melted -- Samba was brought to the rescue. Our author quickly replaced the Windows NT and OS/2 servers with Samba running on a Unix server, and eventually bought PCs for most of the company developers. However, he did the latter without hiring a new PC administrator; the administrator now manages one centralized Unix application instead of fifty distributed PCs.

If you know you're facing a problem with your network and you're sure there is a better way, we encourage you to start reading this book. Or, if you've heard about Samba and you want to see what it can do for you, this is also the place to start. We'll get you started on the path to understanding Samba and its potential. Before long, you can provide Unix services to all your Windows machines -- all without spending tons of extra time or money. Sound enticing? Great, then let's get started.

What is Samba?

Samba is a suite of Unix applications that speak the SMB (Server Message Block) protocol. Many operating systems, including Windows and OS/2, use SMB to perform client-server networking. By supporting this protocol, Samba allows Unix servers to get in on the action, communicating with the same networking protocol as Microsoft Windows products. Thus, a Samba-enabled Unix machine can masquerade as a server on your Microsoft network and offer the following services:

• Share one or more filesystems
• Share printers installed on both the server and its clients
• Assist clients with Network Neighborhood browsing
• Authenticate clients logging onto a Windows domain
• Provide or assist with WINS name server resolution

Samba is the brainchild of Andrew Tridgell, who currently heads the Samba development team from his home of Canberra, Australia. The project was born in 1991 when Andrew created a fileserver program for his local network that supported an odd DEC protocol from Digital Pathworks. Although he didn't know it at the time, that protocol later turned out to be SMB. A few years later, he expanded upon his custom-made SMB server and began distributing it as a product on the Internet under the name SMB Server. However, Andrew couldn't keep that name -- it already belonged to another company's product -- so he tried the following Unix renaming approach:

grep -i 's.*m.*b' /usr/dict/words 

And the response was:

salmonberry samba sawtimber scramble

Thus, the name "Samba" was born.

Which is a good thing, because our marketing people highly doubt you would have picked up a book called "Using Salmonberry"!

Today, the Samba suite revolves around a pair of Unix daemons that provide shared resources -- or shares -- to SMB clients on the network. (Shares are sometimes called services as well.) These daemons are:

smbd

A daemon that allows file and printer sharing on an SMB network and provides authentication and authorization for SMB clients.

nmbd

A daemon that looks after the Windows Internet Name Service (WINS), and assists with browsing.

Samba is currently maintained and extended by a group of volunteers under the active supervision of Andrew Tridgell. Like the Linux operating system, Samba is considered Open Source software (OSS) by its authors, and is distributed under the GNU General Public License (GPL). Since its inception, development of Samba has been sponsored in part by the Australian National University, where Andrew Tridgell earned his Ph.D. [1] In addition, some development has been sponsored by independent vendors such as Whistle and SGI. It is a true testament to Samba that both commercial and non-commercial entities are prepared to spend money to support an Open Source effort.

At the time of this printing, Andrew had completed his Ph.D. work and had joined San Francisco-based LinuxCare.

Microsoft has also contributed materially by putting forward its definition of SMB and the Internet-savvy Common Internet File System (CIFS), as a public Request for Comments (RFC), a standards document. The CIFS protocol is Microsoft's renaming of future versions of the SMB protocol that will be used in Windows products -- the two terms can be used interchangeably in this book. Hence, you will often see the protocol written as "SMB/CIFS."

2. Installing Samba on a Unix System

Contents:
Downloading the Samba Distribution
Configuring Samba
Compiling and Installing Samba
A Basic Samba Configuration File
Starting the Samba Daemons
Testing the Samba Daemons

Now that you know what Samba can do for you and your users, it's time to get your own network set up. Let's start with the installation of Samba itself on a Unix system. When dancing the samba, one learns by taking small steps. It's just the same when installing Samba; we need to teach it step by step. This chapter will help you to start off on the right foot.

For illustrative purposes, we will be installing the 2.0.4 version of the Samba server on a Linux[ 1] system running version 2.0.31 of the kernel. However, the installation steps are the same for all of the platforms that Samba supports. A typical installation will take about an hour to complete, including downloading the source files and compiling them, setting up the configuration files, and testing the server.

[1] If you haven't heard of Linux yet, then you're in for a treat. Linux is a freely distributed Unix-like operating system that runs on the Intel x86, Motorola PowerPC, and Sun Sparc platforms. The operating system is relatively easy to configure, extremely robust, and is gaining in popularity. You can get more information on the Linux operating system at http://www.linux.org /.

Here is an overview of the steps:

1. Download the source or binary files.

2. Read the installation documentation.

3. Configure a makefile.

4. Compile the server code.

5. Install the server files.

6. Create a Samba configuration file.

7. Test the configuration file.

8. Start the Samba daemons.

9. Test the Samba daemons.

2.1 Downloading the Samba Distribution

If you want to get started quickly, the CD-ROM packaged with this book contains both the sources and binaries of Samba that were available as this book went to print. The CD is a mirror image of the files and directories on the Samba download server: ftp.samba.org.

On the other hand, if you want to download the latest version, the primary web site for the Samba software is http://www.samba.org/. Once connected to this page, you'll see links to several Samba mirror sites across the world, both for the standard Samba web pages and sites devoted exclusively to downloading Samba. For the best performance, choose a site that is closest to your own geographic location.

The standard Samba web sites have Samba documentation and tutorials, mailing list archives, and the latest Samba news, as well as source and binary distributions of Samba. The download sites (sometimes called F T P sites) have only the source and binary distributions. Unless you specifically want an older version of the Samba server or are going to install a binary distribution, download the latest source distribution from the closest mirror site. This distribution is always named:

samba-latest.tar.gz

If you choose to use the version of Samba that is located on the CD-ROM packaged with this book, you should find the latest Samba distribution in the base directory.

2.1.1 Binary or Source?

Precompiled packages are also available for a large number of Unix platforms. These packages contain binaries for each of the Samba executables as well as the standard Samba documentation. Note that while installing a binary distribution can save you a fair amount of trouble and time, there are a couple of issues that you should keep in mind when deciding whether to use the binary or compile the source yourself:

• The binary packages can lag behind the latest version of the software by one or two (maybe more) minor releases, especially after a series of small changes and for less popular platforms. Compare the release notes for the source and binary packages to make sure that there aren't any new features that you need on your platform. This is especially true of the sources and binaries on the CD-ROM: at the time this book went to print, they were from the latest production release of Samba. However, development is ongoing, so the beta-test versions on the Internet will be newer.

• If you use a precompiled binary, you will need to ensure that you have the correct libraries required by the executables. On some platforms the executables are statically linked so this isn't an issue, but on modern Unix operating systems (e.g., Linux, SGI Irix, Solaris, HP-UX, etc.), libraries are often dynamically linked. This means that the binary looks for the right version of each library on your system, so you may have to install a new version of a library. The README file or makefile that accompanies the binary distribution should list any special requirements.[ 2]

  [2] This is especially true with programs that use glibc-2.1 (which comes standard with Red Hat Linux 6). This library caused quite a consternation in the development community when it was released because it was incompatable with previous versions of g libc.

  Many machines with shared libraries come with a nifty tool called ldd. This tool will tell you which libraries a specific binary requires and which libraries on the system satisfy that requirement. For example, checking the smbd program on our test machine gave us:

$ ldd smbd

libreadline.so.3 => /usr/lib/libreadline.so.3
libdl.so.2 => /lib/libdl.so.2
libcrypt.so.1 => /lib/libcrypt.so.1
libc.so.6 => /lib/libc.so.6
libtermcap.so.2 => /lib/libtermcap.so.2
/lib/ld-linux.so.2 => /lib/ld-linux.so.2

• If there are any incompatibilities between Samba and specific libraries on your machine, the distribution-specific documentation should highlight those.

• Keep in mind that each binary distribution carries preset values about the target platform, such as default directories and configuration option values. Again, check the documentation and the makefile included in the source directory to see which directives and variables were used when the binary was compiled. In some cases, these will not be appropriate for your situation.

  A few configuration items can be reset with command-line options at runtime instead of at compile time. For example, if your binary tries to place any log, lock, or status files in the "wrong" place (for example, in /usr/local ), you can override this without recompiling.

One point worth mentioning is that the Samba source requires an ANSI C compiler. If you are on a platform with a non-ANSI compiler, such as the cc compiler on SunOS version 4, you'll have to install an ANSI-compliant compiler such as gcc before you do anything else.[ 3] If installing a compiler isn't something you want to wrestle with, you can start off with a binary package. However, for the most flexibility and compatibility on your system, we always recommend compiling from the latest source.

[3] gcc binaries are available for almost every modern machine. See http://www.gnu.org/ for a list of sites with gcc and other GNU software.

2.1.2 Read the Documentation

This sounds like an obvious thing to say, but there have probably been times where you have uncompressed a package, blindly typed configure, make, and make install, and walked away to get another cup of coffee. We'll be the first to admit that we do that, many more times than we should. It's a bad idea - especially when planning a network with Samba.

Samba 2.0 automatically configures itself prior to compilation. This reduces the likelihood of a machine-specific problem, but there may be an option mentioned in the README file that you end up wishing for after Samba's been installed. With both source and binary packages you'll find a large number of documents in the docs directory, in a variety of formats. The most important files to look at in the distribution are:

WHATSNEW.txt
docs/textdocs/UNIX_INSTALL.txt

These files tell you what features you can expect in your Samba distribution, and will highlight common installation problems that you're likely to face. Be sure to look over both of them before you start the compilation process.