Ubuntu Unleashed 2017 Edition (2017)

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The valid users entry limits userid to just mhelmke. All other users can browse the directory because of the browseable = yes entry, but only mhelmke can write to the directory. Any files created by ahudson in the directory give ahudson full permissions, but no one else will have access to the file. This is the same as setting permissions with the chmod command. Again, there are numerous options, so you can be as creative as you want when developing sections.

Setting Global Samba Behavior with the [global] Section

The [global] section set parameters establishes configuration settings for all of Samba. If a given parameter is not specifically set in another section, Samba uses the default setting in the [global] section. The [global]section also sets the general security configuration for Samba. The [global] section is the only section that does not require the name in brackets.

Samba assumes that anything before the first bracketed section not labeled [global] is part of the global configuration. (Using bracketed headings in /etc/samba/smb.conf makes your configuration file more readable.) The following sections discuss common Samba settings to share directories and printers. You will then see how to test your Samba configuration.

Sharing Home Directories Using the [homes] Section

The [homes] section shares out Ubuntu /home directories for the users. The /home directory is shared automatically when a user’s Windows computer connects to the Linux server holding the /home directory. The one problem with using the default configuration is that the users see all the configuration files (such as .profile and others with a leading period in the filename) that they normally wouldn’t see when logging on through Linux. One quick way to avoid this is to include a path option in the [homes] section. To use this solution, any users who require a Samba share of their /home directory need a separate “home directory” to act as their Windows /home directory.

This setting specifies that the directory named share under each user’s directory is the shared Samba directory. The corresponding manual smb.conf setting to provide a separate “home directory” looks like this:

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[homes]
comment = Home Directories
path = /home/%u/share
valid users = %S
read only = No
create mask = 0664
directory mask = 0775
browseable = No

If you have a default [homes] section, the share shows up in the user’s Network Neighborhood as the user’s name. When the user connects, Samba scans the existing sections in smb.conf for a specific instance of the user’s /home directory. If there is not one, Samba looks up the username in /etc/passwd. If the correct username and password have been given, the home directory listed in /etc/passwd is shared out at the user’s /home directory. Typically, the [homes] section looks like this. (The browseable = no entry prevents other users from being able to browse your /home directory and is a good security practice.)

[homes]
browseable = no
writable = yes

This example shares out the /home directory and makes it writeable to the user. Here’s how you specify a separate Windows /home directory for each user:

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[homes]
browseable = no
writable = yes
path = /path/to/windows/directories

Sharing Printers by Editing the [printers] Section

The [printers] section works much like the [homes] section but defines shared printers for use on your network. If the section exists, users have access to any printer listed in your Ubuntu /etc/printcap file.

Like the [homes] section, when a print request is received, all the sections are scanned for the printer. If no share is found (with careful naming, there should not be unless you create a section for a specific printer), the /etc/printcap file is scanned for the printer name that is then used to send the print request.

For printing to work properly, you must correctly set up printing services on your Ubuntu computer. A typical [printers] section looks like this:

[printers]
comment = Ubuntu Printers
browseable = no
printable = yes
path = /var/spool/samba

The /var/spool/samba is a spool path set just for Samba printing.

Testing Samba with the testparm Command

After you have created your /etc/smb.conf file, you can check it for correctness by using the testparm command. This command parses through your /etc/smb.conf file and checks for any syntax errors. If none are found, your configuration file will probably work correctly. It does not, however, guarantee that the services specified in the file will work. It is merely making sure that the file is correctly written.

As with all configuration files, if you are modifying an existing, working file, it is always prudent to copy the working file to a different location and modify that file. Then, you can check the file with the testparm utility. The command syntax is as follows:

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matthew@seymour:~$ sudo testparm /path/to/smb.conf.back-up
Load smb config files from smb.conf.back-up
Processing section "[homes]"
Processing section "[printers]"
Loaded services file OK.

This output shows that the Samba configuration file is correct, and as long as all the services are running correctly on your Ubuntu machine, Samba should be working correctly. Now copy your old smb.conf file to a new location, put the new one in its place, and restart Samba with the command sudo smbd restart. Your new or modified Samba configuration should now be in place.

Starting, Stopping, and Restarting the smbd Daemon

After your smb.conf file is correctly configured, you might want to start, stop, or restart your Samba server daemon. You can do this with the /usr/sbin/smbd command, which (with no options) starts the Samba server with all the defaults. The most common option you will change in this command is the location of the smb.conf file; you change this option if you don’t want to use the default location /etc/smb/smb.conf. The -s option enables you to change the smb.conf file Samba uses; this option is also useful for testing whether a new smb.conf file actually works. Another useful option is the -l option, which specifies the log file Samba uses to store information.

To start, stop, or restart Samba from the command line, use this, replacing start with either stop or restart as appropriate:

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matthew@seymour:~$ sudo start smbd

Using the smbstatus Command

The smbstatus command reports on the current status of your Samba connections. The syntax is as follows:

/usr/bin/smbstatus [options]

Table 23.2 shows some of the available options.

TABLE 23.2 smbstatus Options

Connecting with the smbclient Command

The smbclient command allows users on other Linux hosts to access your smb shares. You cannot mount the share on your host, but you can use it in a way that is similar to an FTP client. Several options can be used with the smbclient command. The most frequently used is -I followed by the IP address of the computer to which you are connecting. The smbclient command does not require root access to run:

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matthew@seymour:~$ smbclient -I 10.10.10.20 -Uusername%password

This gives you the following prompt:

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smb: <current directory on share>

From here, the commands are almost identical to the standard UNIX/Linux FTP commands. Note that you can omit a password on the smbclient command line. You are then prompted to enter the Samba share password.

Mounting Samba Shares

There are two ways to mount Samba shares to your Linux host. Mounting a share is the same as mounting an available media partition or remote NFS directory except that the Samba share is accessed using SMB. The first method uses the standard Linux mount command:

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matthew@seymour:~$ sudo mount -t smbfs //10.10.10.20/homes /mount/point -o
username=heather,dmask=777,\ fmask=777