Linux CIFS Utils and Samba

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Samba was developed by a team by using "network analysis" or "protocol analysis" to create file and print services to Microsoft Windows clients and servers. Samba is free open source software. Samba makes possible interoperability between Linux/Unix servers and Windows-based clients and servers. Samba originally worked with SMB (Server Message Block) to communicate with Windows machines. Today CIFS (Common Internet File System) is used instead. As a footnote, Samba dates back to 1992!

Server Message Block (SMB) protocol, also called the Session Message Block, NetBIOS or LanManager protocol.

What are the differences between CIFS and SAMBA?

Today Samba implements the CIFS network protocol to work with changes Microsoft has made in their Windows networking platform. CIFS is the extension of the SMB protocol. The in-kernel CIFS filesystem is generally the preferred method for mounting SMB/CIFS shares on Linux.

The original protocol for sharing files, disks, directories, and printers across a network of Microsoft machines was by use of Server Message Block. There are underlying protocols involved with SMB with some examples being: "NetBIOS over NetBEUI" and "NetBIOS over TCP/IP" Samba traditionally required "NetBIOS over TCP/IP" and didn't support "NetBIOS over NetBEUI." This is fine as NetBEUI is not Internet routable and is not a currently support protocol, even by Microsoft. WINS is for resolving a NetBIOS name to an IP address, however, modern implementations avoid NetBIOS usage though Internal DNS.

CIFS pretty much takes care of all connectivity on a network for your *nix machines and Microsoft Windows. However, Samba does still support SMB and an example where this is useful may be if sharing with older Windows operating systems still using NetBIOS that will want to connect to the Samba server via port 137, 138, 139. The modern CIFS protocol is strictly port 445. This is 'smbfs' versus the modern 'cifs' in Linux.

Microsoft is the industry bully, trying to lay claim to protocols and technologies developed by others. Microsoft tried to claim SMB as their own by calling it Microsoft Networking. The company was a force behind the renaming of SMB (Server Message Block) to CIFS (Common Internet File System.)

The cifs utils Package

The cifs-utils package is available for modern Linux kernels as the protocol is supported directly in the kernel. The cifs-utils package is not part of Samba, although they were originally included with it. Today you do not need to install Samba to have cifs-utils. Install the cifs-utils package for connectivity to Microsoft Networks. Samba is not deprecated. Samba provides both cifs and smb support, and comes with many additional tools. For basic connectivity to a modern Microsoft Windows Network, Samba is simply no longer necessary.

This documentation is largely Linux centric and cifs-utils is a package for Linux systems. Under distributions such as Debian and Ubuntu you can check to see if you have cifs-utils installed and what version it is by typing the command: (as root or sudo) 

apt-cache policy cifs-utils

To install cifs-utils on a modern debian or ubuntu system 

apt-get install cifs-utils

To install cifs-utils on an old legacy system 

apt-get install smbfs

To install cifs-utils on Redhat / Fedora / CentOS 

yum install cifs-utils

Or to install everything, for cifs / smb on RH 

yum install samba-client samba-common cifs-utils

Mounting Windows shares on your Linux system

You can mount a share with a console command to make a temporary mount until the next reboot, or you can add an entry into fstab to make a persistent mount.

You have to create an empty directory for the mount point. This should be done in /mnt for all mount points you create.

command line mount

Quick basic examples of command line mounts 

mount -t cifs -o username=USERNAME,password=PASSWD //192.168.1.88/shares /mnt/share
mount -t cifs //192.168.1.102/share_name /media/my_share -o username=theuser,password=thepass,iocharset=utf8,file_mode=0777,dir_mode=0777

fstab persistent mount

Quick basic example of a cfis mount entry in fstab to connect to shares on a Windows file server or NAS device. A discussion of windows network share integration for linux points out the flaws in this approach.

There are more than one ways to do this. This example uses cifs to permanently mount the shares so that they will be available after reboot. If the system complains add the 'noauto' parameter.

  • First edit your /etc/hosts file and add the hostname and IP address of the windows share or file server
  • Next create mount points in /mnt for each windows share
  • Make sure you have cifs installed
  • Edit /etc/fstab and add a line for each windows share, see examples: 
//apollo/public/ /mnt/public cifs username=nicolep,password=mythtv,iocharset=utf8,sec=ntlm  0  0
//apollo/media/ /mnt/media cifs username=nicolep,password=mythtv,iocharset=utf8,sec=ntlm  0  0
//apollo/video/ /mnt/video cifs username=nicolep,password=mythtv,iocharset=utf8,sec=ntlm  0  0
  • mount the shares 
mount -a
  • This provides read-only access to the network shares.

KERNEL CHANGE BREAKS CIFS.

Somewhere between kernel 4.10.0-38 4.15.0-20 a change was made that COULD PREVENT your cifs shares from mounting. Kernels at and before 4.10 used SMB (Server Message Block) version 1.0 as the default if not specified. Most folks did not specify it so it defaulted to 1.0 and worked. Microsoft ditched 1.0 in Windows 10 and dropped support. Linux kernel developers decided to change the kernel code to no longer default to SMB 1.0 and now default to a newer version. For people that are using legacy networks or NAS devices, it breaks the mounting example from above.

Solution: Specify the SMB version.

The solution is to tell mount.cifs to use the SMB2, SMB2.1 or SMB3.0 protocol using the "vers" parameter. in Linux CIFS Utils and Samba Specify 1.0, 2.0, 2.1, or 3.0.

For the following full line example a linux desktop is connecting to an older NAS device. It is necessary to specify SMB version 1.0. Example: 

//apollo/video/ /mnt/video cifs defaults,vers=1.0,domain=workgroup,username=nicolep,password=mythtv,iocharset=utf8,sec=ntlm 0 0

SMB protocol versions

According to the Samba Official Wiki the Linux cifs kernel client has been included in the kernel since kernel version 2.5.42. SMB3 is the now the default dialect (SMB3.02/SMB3/SMB2.1 dialects are requested by default). CIFS protocol (and other old dialects) can be selected (by specifying "vers=1.0" or "vers=2.02" in the mount options. The newest, most secure dialect, SMB3.11 can also be requested (vers=3.1.1). If you want to try current SMB3 support on an older kernel, full backports of all SMB3/CIFS fixes to earlier kernel versions.

SMB versions:

  • 1.0 - The classic CIFS/SMBv1 protocol.
  • 2.0 - The SMBv2.002 protocol. This was initially introduced in Windows Vista Service Pack 1, and Windows Server 2008. Note that the initial release version of Windows Vista spoke a slightly different dialect (2.000) that is not supported.
  • 2.1 - The SMBv2.1 protocol that was introduced in Microsoft Windows 7 and Windows Server 2008R2.
  • 3.0 - The SMBv3.0 protocol that was introduced in Microsoft Windows 8 and Windows Server 2012.
  • 3.11 - latest

all mounted files and directories owned by root

Yes by default all the files and directories will be owned by the uid of the process or by root. You can force it otherwise. 

sudo id user_name

If, for example, the user id is 1000 then you can use the following... 

uid=1000(user_name) gid=1000(user_name) groups=...

Make the following entry in your /etc/fstab file : 

//server_name/share_name /mount_path cifs defaults,uid=1000,gid=1000 0 0

Now when the share is mounted all files and folders will appear as the user with uid 1000. This is fine if you are the only user of the system. On a multiuser system this is problematic as other users will still be denied. Another option is to use dir_mode / file_mode to give everyone access: 

dir_mode=0777,file_mode=0666

which will look like: 

//server_name/share_name /mount_path cifs defaults,dir_mode=0777,file_mode=0666 0 0

gvfs

GVFS is the virtual filesystem for the GNOME desktop, which allows users easy access to remote data such as accessing windows network shares on demand from your linux workstation.

GVFS is discussed in Windows network share integration for linux as well as being compared to creating static mounts in fstab.

Share a Linux drive with Windows over the network

The question, "how do I do a share a Linux drive with Windows over the network?" is answered with CIFS/SMB.

You can use Samba Utils (debian/ubuntu) 

sudo apt-get install system-config-samba

Or you can manually edit the samba config files 

vi /etc/samba/smb.conf

See: Example Mythbuntu SMB Shares

Restart samba after modifying workgroup and shares 

service smbd restart
service nmbd restart

If an error indicates smbd does not exist then you may need to install samba, even though a config file exists ( /etc/samba/smb.conf ) the samba package can be absent on Ubuntu / Mint. 

apt install samba

resources

Ubuntu users may wish to read [https://wiki.ubuntu.com/MountWindowsSharesPermanently MountWindowsSharesPermanently] on the Ubuntu Wiki. It is a guide to how to mount CIFS shares permanently.

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