6.2 Special Sections

Now that we've gotten our feet wet with variables , there are a few special sections of the Samba configuration file that we should talk about. Again, don't worry if you do not understand every configuration option listed here; we'll go over each of them in the upcoming chapters.

6.2.1 The [ global] Section

The [global] section appears in virtually every Samba configuration file, even though it is not mandatory. There are two purposes for the [global] section. Server-wide settings are defined here, and any options that apply to shares will be used as a default in all share definitions, unless overridden within the share definition.

To illustrate this, let's again look at the example at the beginning of the chapter:

 [global]     workgroup = METRAN     encrypt passwords = yes     wins support = yes     log level = 1      max log size = 1000     read only = no [homes]      browsable = no     map archive = yes [printers]      path = /var/tmp     printable = yes     min print space = 2000 [test]     browsable = yes     read only = yes     path = /usr/local/samba/tmp 

When a client connects to the [test] share, Samba first reads the [global] section and sets the option read only = no as the global default for each share it encounters throughout the configuration file. This includes the [homes] and [test] shares. When it reads the definition of the [test] share, it then finds the configuration option read only = yes and overrides the default from the [global] section with the value yes .

Any option that appears before the first marked section is assumed to be a global option. This means that the [global] section heading is not absolutely required; however, we suggest you always include it for clarity and to ensure future compatibility.

6.2.2 The [ homes] Section

If a client attempts to connect to a share that doesn't appear in the smb.conf file, Samba will search for a [homes] share in the configuration file. If a [homes] share exists, the unresolved share name is assumed to be a Unix username. If that username appears in the password database on the Samba server, Samba assumes the client is a Unix user trying to connect to her home directory on the server.

For example, assume a client system is connecting to the Samba server toltec for the first time and tries to connect to a share named [alice] . There is no [alice] share defined in the smb.conf file, but there is a [homes] , so Samba searches the password database file and finds an alice user account is present on the system. Samba then checks the password provided by the client against user alice 's Unix password ”either with the password database file if it's using nonencrypted passwords or with Samba's smbpasswd file if encrypted passwords are in use. If the passwords match, Samba knows it has guessed right: the user alice is trying to connect to her home directory. Samba will then create a share called [alice] for her, with the share's path set to alice 's home directory.

The process of using the [homes] section to create users (and dealing with their passwords) is discussed in more detail in Chapter 9.

6.2.3 The [printers] Section

The third special section is called [printers] and is similar to [homes] . If a client attempts to connect to a share that isn't in the smb.conf file and its name can't be found in the password file, Samba will check to see if it is a printer share. Samba does this by reading the printer capabilities file (usually /etc/printcap ) to see if the share name appears there. ^[1] If it does, Samba creates a share named after the printer.

^[1] Depending on your system, this file might not be /etc/printcap . You can use the testparm command that comes with Samba to dump the parameter definitions and determine the value of the printcap name configuration option. The value assigned to it is the default value chosen when Samba was configured and compiled, which should be correct.

This means that as with [homes] , you don't have to maintain a share for each system printer in the smb.conf file. Instead, Samba honors the Unix printer registry if you ask it to, and it provides the registered printers to the client systems. However, there is a potential difficulty: if you have an account named fred and a printer named fred , Samba will always find the user account first, even if the client really needed to connect to the printer.

The process of setting up the [printers] share is discussed in more detail in Chapter 10.