What is Server Message Block (SMB)?

Server Message Block (SMB)

A client/server protocol called SMB (Server Message Block) controls access to files, whole directories, and other network resources, including printers, routers, and network interfaces. The SMB protocol may be used to handle information sharing between the various processes in a system, sometimes referred to as inter-process communication.

The protocol was created in 1983 by IBM's IT division, and throughout the years, it has undergone several revisions and implementations. SMB was initially made accessible to the general public as a feature of the OS/2 LAN Manager and LAN Server network operating systems. Since the Windows operating system series' network services are backwardcompatible with SMB, they have been the protocol's primary application.

This makes it simple for devices running newer editions of Microsoft operating systems to connect with those running older versions. Additionally, the open-source Samba project provides a method for using Server Message Block in Linux and Unix distributions, enabling cross-platform SMB communication.

The network basic input/output system (NetBIOS) and the NetBIOS extended user interface (NetBEUI), via which SMB is designed to operate, are as follows −

Frame for NetBIOS

  • IPX/SPX, also known as NetBIOS via Internetwork Packet Exchange,

  • Transmission Control Protocol/Internet Protocol (TCP/IP) and NetBIOS

Features of NetBIOS

  • Use desktops and servers running Windows

  • Includes Samba protocol daemons for Unix and systems that are similar to Unix

  • Enables NetBIOS transfer across older versions of Windows

  • Utilizes NetBIOS transport services known as Network Neighborhood (NetHood) protocols.

  • Use Distributed Computing Environment/Remote Procedure Call (DCE/RPC) services to authenticate multiprocess communication channels.

How Does SMB Function?

The client may interact with other users on the same network using the Server Message Block protocol, giving it access to any files or services that are made available to it on the network. In order for this to function, the other machine must also have the network protocol installed and use an SMB server program to accept and handle the relevant client request. However, in order to create a link, both parties must first send equivalent messages to one another.

SMB employs the Transmission Control Protocol (TCP) in IP networks, which enables a three-way handshake between the client and server before a connection is established. The TCP protocol's rules govern the carriage of subsequent data.

Where Can I Utilize a Server Message Block?

In this post, the key SMB application scenarios have already been covered. The main advantages of the protocol are found in client/server interactions between computers and file servers since access to file systems is its primary focus. Simple data exchange between two devices or two processes, however, belongs to its application profile because other elements of the protocol are obviously intended for inter-process communication.

Along with being included in the different Windows versions, Server Message Block was also incorporated into a large number of other software projects to allow communication between entities beyond the Microsoft family. The following are some of the most well-known SMB implementations −

  • Samba − The computer program The most well-known SMB implementation outside of Windows is likely Samba. Programmer Andrew Tridgell began creating the opensource software in 1991 that permits communication on Unix/Linux systems using the Server Message Block protocol.

  • Netsmb − The SMB client and server are implemented directly in the kernel of BSD operating systems. They were initially made available for FreeBSD 4.4, but are now supported by a number of BSD operating systems, including NetBSD and macOS.

  • YNQ − Since 1998, Visuality Systems Ltd., an Israeli software startup, has been working on YNQ.

  • FreeNAS − The OpenZFS file system and FreeBSD serve as the foundation for the NAS software.

  • ConnectedNAS − ConnectedNAS Users of the premium software may quickly transfer data privately or between SMB devices using their mobile device and other SMB devices. The only SMB protocols that ConnectedNAS supports are those from version 2

SMB Versions

The network standard has undergone several modifications since SMB was initially introduced in 1983, which are reflected in the different protocol versions. These range from SMB 1.0 through the most recent version, SMB 3.1.1, which Microsoft unveiled alongside Windows 10. The essential phases in the creation of the Server Message Block protocol are outlined in the sections that follow.

The main dialects of SMB include −

  • CIFS/SMB 1.0

  • SMB 2.0

  • SMB 2.1

  • SMB 3.0

  • SMB 3.02

  • SMB 3.1.1

SMB Encryption

SMB Encryption offers end-to-end encryption of SMB data and guards against data theft on unsecured networks. SMB Encryption can be set up with little work, although it can cost a little extra for specialist hardware or software. It doesn't need WAN accelerators or Internet Protocol security (IPsec). SMB Encryption may be set for a number of situations when data travels over untrusted networks and can be configured either per share or across the board for the file server.