Server Administration

Linux file server using Samba

Linux file server is one of the powerful servers that helps you to share files and printers with Windows-based PCs and other operating systems. Before we talk about using Samba as a file server, let’s discuss some basics.

 

 

Linux/Samba/Windows relationship

To understand Linux/Samba/Windows relationship, you need to understand the relationships of the operating systems, users, and networks.

Linux login system is different from the Windows login system.

So, it’s the system administrator’s job to maintain the logins between different platforms.

There are several solutions to do this:

  • Linux pluggable authentication modules (PAMs): there are two user lists, one local list and one on the domain controller (DC), and users need to maintain their passwords only on the Windows system.
  • Samba as a DC: you maintain usernames and passwords on the Linux system, and users can log in to Windows boxes with Samba
  • Custom script: you can create scripts for maintaining logins and passwords; this can be done using a cross-platform scripting language like python.

The samba server composed of several components and daemons; the three main daemons are smbd, nmbd, and winbindd.

  • The smbd daemon is the main service for the sharing of files and printers. This daemon uses port 139 or 445 to listen for requests.
  • The nmbd daemon handles NetBIOS name service requests. This daemon uses port 137 to listen for requests.
  • The winbindd gets the user and group information from Windows.

 

Install Samba

To install the Linux file server, you need to install three packages.

For Red Hat based distros, you can install them like this:

$ dnf -y install samba

This package installs the SMB server.

$ dnf -y install samba-common-tools

This package includes the required files for both the server and the client.

$ dnf -y install samba-client

For Debian based distros, you can install them like this:

$ apt-get -y install samba

$ apt-get -y install samba-common-tools

$ apt-get -y install samba-client

Then you can start samba service and enable it at startup:

$ systemctl start smb

$ systemctl enable smb

 

Samba file sharing

Of course, you can use web-based or GUI utilities to manage your Linux file server. However, it is useful to understand what GUI or web tools are doing from behind.

Now we will share a folder named myfolder:

$ chmod -R 755 myfolder

Open up Samba configuration file

/etc/samba/smb.conf

and add the following lines at the end:

[likegeeks]

path=/home/likegeeks/Desktop/myfolder

public=yes

writable=no

guest ok=yes

The first line is the Samba server name that the clients see.

The second line is the path to the folder that will be shared.

The third line means the share will be available to all users like guest account and others. If set to no, this will allow authenticated and permitted users only.

The fourth line means that you cannot create or modify the stored files on the shared folder.

You can check for SMB configuration errors using the testparm command:

$ testparm

Now restart SMB service:

$ systemctl restart smb

 

Access Samba shared files

Now we need to access what we’ve shared. We can use the smbclient utility to access Windows shared files.

We can list the shared files like this:

$ smbclient -L localhost -U%

The -U% option here to avoid asking for the password.

Linux file server

As you can see, our shared folder is on the list.

You can access this shared folder from Windows by just typing the IP address in the Windows explorer.

\\192.168.1.3\

You can list a specific directory using the smbclient tool like this:

$ smbclient -U% //192.168.1.2/My_Folder

Once you’ve connected, you can use Linux commands to list and travel between files.

You can transfer files using the get, put, mget, and mput commands.

If you are using the iptables firewall, don’t forget to allow the ports 137,139 and 445.

 

Mounting Samba Shares

Most Linux kernels support the SMB file system.

To mount a Samba share, First, create a mount point:

$ mkdir /mnt/smb

Then we mount the SMB shared folder:

$ mount -t cifs -o guest //192.168.1.2/My_Folder /mnt/smb

If the shared folder is password-protected, then you type the username and password:

$ mount -t cifs username=likegeeks,password=mypassword //192.168.1.2/My_Folder

To unmount the SMB shared folder, use the unmount command like this:

$ umount /mnt/smb

On Debian based distros, you might need installing the cifsutils package to use it:

$ apt-get -y install cifs-utils

 

Creating Samba users

To create a samba entry for an existing system user, use the pdbedit command:

$ pdbedit -a likegeeks

The new user will be created in the Samba default user database which is

/var/lib/samba/private/passdb.tdb

file.

With a Samba user created, we can make the shares available only to authenticated users like the user likegeeks.

This user can access his resources on Samba server using smbclient like this:

$ smbclient -U likegeeks -L //192.168.1.3

You can use the smbpasswd command to change the SMB password like this:

$ smbpasswd likegeeks

 

Authenticate users using Windows server

You can use the winbindd daemon for resolving user accounts information from native Windows servers.

First, install the winbind package.

$ dnf -y install samba-winbind

Then start the service like this:

$ systemctl start winbind

After that, add the following options in this file:

/etc/samba/smb.conf
workgroup = windows-domain

password server = 192.1638.1.5

realm = windows-domain.com

kerberos method = secrets and keytab

winbind use default domain = yes

winbind enum users = yes

winbind enum groups = yes

winbind refresh tickets = yes

winbind normalize names = yes

winbind nss info = rfc2307

domain master = no

local master = no

Then edit the /etc/nsswitch.conf file and modify the following lines:

passwd: files winbind

shadow: files winbind

group: files winbind

Then edit the /etc/resolv.conf  file and change the primary DNS server:

Search windows-domain.com

nameserver 192.168.1.5

Now join the Linux Samba server from the Windows domain using the net command:

$ net join -w WINDOWS-DOMAIN -s ' win-server' -U Administrator%password

You can list the users in the Windows domain using wbinfo command

$ wbinfo -u

For any problem diagnostics, you can check the samba log files under

/var/log/samba/

directory, also use testparm utility to check your configuration after you modify the samba configuration file.

That’s all. I hope you find the Linux file server easy. Keep coming back.

Thank you.

Mokhtar Ebrahim
Founder of LikeGeeks. I'm working as a Linux system administrator since 2010. I'm responsible for maintaining, securing, and troubleshooting Linux servers for multiple clients around the world. I love writing shell and Python scripts to automate my work.

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