Samba: installation and configuration. Lab.

In-class lab: installation and configuration of Samba

Samba is a software package that comes with most Linux systems. Samba enables you to share file systems and printers on a network with computers that use the Server Message Block (SMB) or Common Internet File System (CIFS) protocols. SMB is the Microsoft protocol that is delivered with Windows operating systems for sharing files and printers. CIFS is an open, cross-platform protocol that is based on SMB. Samba contains implementations of both.

Installation

First, check if samba is not yet installed on your machine by running

# yum list | grep samba

if you see the line that looks like: samba-3.0.82 fedora it means that this package is part of the Fedora but not yet installed. In this case, install the last approved version of samba by running yum install samba

Now, please go to the /etc/init.d directory and make sure that the startup script for samba (smb) is there. Check the current status of the samba service by running service smb status. If the service is not running, start it by means of service smb start. If you do not want to manually start the service every time you reboot your system, configure it to run automatically. This can be done by using the chkconfig command:

# chkconfig --add smb

Now, the smb service is running but we still cannot access it from outside because the ports for samba server are not open in firewall. Please run System/Administrations/Firewall

and make sure you open the ports used by samba service.

Simple configuration

There are three ways of configuring samba server:

manually edit the configuration file
Use samba configuration program with GUI
Use web interface

Manual configuration

Samba configuration file is called smb.conf and located in the /etc/samba directory. This is a pure text file with a lot of comments that explain pretty much any detail of the file instruction. In order to practice with the file a little bit, let's create a directory that can be shared by some users.

create a directory which you will share in the future (let's say /var/smbshare)
go to the /etc/samba directory and make a backup copy of smb.conf
open the smb.conf file and scroll down to the very end of the file. You should find yourself in the Share definitions section
append the following lines to the file
```
[smbshare]
	comment = Public share
	path = /var/smbshare
;	writeable = yes
;	browseable = yes
	valid users = mary
 
```
What we just entered means: we create a new smb share named smbshare (see square brackets), path to which is defined as /var/smbshare, the only user who can access it is mary. Please note the semicolon at the beginning of the writeable=no line. Semicolon means the same as the pound sign (£) – comments.
we are almost ready to check how it works except one thing – user authentication. According to the default settings, samba authentication uses individual user's authentication and their encrypted passwords. In order to add another samba user, we need to use smbpasswd command. Thus, to create samba user mary run:
```
# smbpasswd -a mary
```
and type a password for this user.
Do not forget to restart the samba service in order for new setting to take an effect:
```
# service smb restart
```
One last touch is to let the Linux security program SELinux access information in the shared directories. Please start Applications/System Tools/SELinux Management and check the samba settings as shown in the Figure below.
You can achieve the same result by running the following commands from the shell:
```
 # setsebool -P samba_export_all_ro=1
 # setsebool -P samba_export_all_rw=1
 # setsebool -P samba_enable_home_dirs=1
 
```

We are done with the manual configuration. Now, let's see if this sharing actually works. Please do the following:

create a test file in the shared directory: echo test > /var/smbshare/testfile.txt
find out the IP address of your Linux machine: ifconfig
switch to your Windows machine
in the command prompt run the following command:
```
c:\> net use Q: \\192.168.183.128\smbshare /persistent:no /user:mary password
```
Instead of password, use the password you entered at the prompt of the smbpasswd command when you were creating samba user mary.
If everything works correctly, you should be able to see the Q: disk now and the file testfile.txt you created there.
Also try to connect to \\IP\homes share.

Using samba configuration program

A special program provides a nice window interface to samba configuration. In fact, this program does nothing but writing special instructions into the smb.conf file but it does it without typos :). To run the program, go to System/Administration and look for Samba tools. If it's not present, install it by

# yum install system-config-samba

Once it's installed, run it and enter the root password at the prompt. You'll see a window like the one below

but with the smbshare already listed. Play with the program to add another user bobby and let this user access the smbshare share.

Configuring with SWAT

Samba Web Administration Tool (SWAT) is a samba configuration tool that can be accessed through any web browser. To install it, run yum install samba-swat. Once installed, we need to turn the swat service on by running chkconfig swat on and actually starting it. The difference between the swat service and other services we have looked at is that the swat service is executed through the xinetd service. Thus, in order to start it, we have to restart the xinetd. This can be done by service xinetd reload. If the swat service successfully started, we can now access it through a web browser.

To configure samba server through the web interface, start a web browser from your Linux machine and go to the http://localhost:901

At the authentication prompt enter the super user's credentials. Using this tool create another share and make sure it works just as well as GUI configuration.

Additional practice

Using the smbpasswd command create a couple more samba users
Through the GUI samba config tool let all these users access the smbshare directory
Open the smb.conf file and see how all these users are added to the valid users value
Try to use valid users = %U instead. Describe what this does.
Uncomment the "; browseable=yes" line and explain what this does.
Uncomment the "; writeable=yes" line and try to write something to the share from the Windows computer. Was this attempt successfull? If not, why do you think it wasn't and what needs to be done to make the write possible?

Using SMB protocol to access Windows shares from Linux machines

In order to access Windows share from your Linux machine, you need to use the mount command with appropriate file system specified and the full address of the network share. Let's test this by doing the following:

On your Windows machine create a share (let's say c:\temp\winshare named winshare) accessible by yourself

on Linux machine create a directory /mnt/smb and run the following command:

# mount -t cifs -o username=your_login> //ip_of_windows_machine/winshare /mnt/smb

Now, make sure it works by going to /etc/smb directory and trying to transfer file back and forth between the Windows and Linux machines

Additional reading

Chapter 18 from the course textbook
Official Samba web site
smb.conf file
Wikipedia article about SMB protocol