Server Message Block protocol (SMB protocol)

What is the Server Message Block protocol?

A client-server communication mechanism called Server Message Block Protocol (SMB protocol) is used to share network resources, including files, printers, serial ports, and other resources. Additionally, transaction protocols for interprocess communication can be carried by it. SMB has historically been used to link Windows machines, while the majority of other operating systems, including Linux and macOS, also include client components that allow them to connect to SMB resources.

In the 1980s, a team at IBM created the SMB protocol. Since then, the protocol has given rise to several variations, or dialects, to accommodate changing network needs. SMB has been used extensively at that period and is still regarded as one of the most regularly used options for file sharing in the office.

How is the SMB protocol implemented?

Applications and their users may connect to printers, mail slots, named pipes, and other resources by using the SMB protocol to access files on distant servers. Client programs may access, read, move, create, and update files on distant servers safely and under control with the help of SMB. Additionally, server programs set up to handle SMB client queries may interact with the protocol.

The SMB protocol, sometimes referred to as a response-request protocol, is one of the most widely used techniques for network communications. In this approach, the connection is established by the client sending an SMB request to the server. After receiving the request, the server responds by providing the client with an SMB response, opening the channel of communication required for a two-way exchange.

Although the SMB protocol uses lower network layers for transit, it functions at the application layer. SMB formerly operated on top of outdated protocols like Internetwork Packet Exchange and NetBIOS Extended User Interface, as well as Network Basic Input/output System over Transmission Control Protocol/Internet Protocol (NetBIOS over TCP/IP, or NBT), although to a lesser extent. SMB depended on ports 137, 138, and 139 for transfer while using NBT. These days, SMB utilizes port 445 and operates natively over TCP/IP.

These days, NetBIOS must be used via a transport protocol like TCP/IP in order to communicate with devices that do not support SMB natively over TCP/IP.

Microsoft Windows operating systems have supported the SMB protocol since Windows 95. SMB is also supported by default in Linux and macOS. Samba may also be used by Unix-based computers to provide SMB access to file and print services.

Different SMB languages may be implemented by a client and a server. If they do, before a session can begin, the systems have to work out the variations across versions.

What are SMB protocol dialects?

Numerous SMB languages have been made available since the SMB protocol was first launched, improving upon the first implementation and offering more scalability, security, efficiency, and features. Below is a quick summary of the most prominent dialects:

• SMB 1.0 (1984): IBM developed SMB 1.0 for DOS file sharing. In order to lessen network traffic, it added opportunistic locking, or OpLock, as a client-side caching approach. Later on, Microsoft would include the SMB protocol into its LAN Manager software.
• CIFS (1996): Windows 95 saw the release of CIFS, an SMB dialect created by Microsoft. CIFS, an acronym for Common Internet File System, introduced support for greater file sizes, TCP/IP direct transfer, and hard and symbolic connections.
• SMB 2.0 (2006): SMB 2.0 was made available with Windows Server 2008 and Vista. It provided support for wide area network (WAN) acceleration, improved scalability and resilience, and decreased chattiness to increase performance.
• SMB 2.1 (2010): Windows Server 2008 R2 and Windows 7 brought SMB 2.1. To strengthen caching and boost speed, OpLock was replaced with the client OpLock leasing model. Improved energy economy and support for big maximum transmission units were two further improvements that allowed clients with open files from an SMB server to go into sleep mode.
• SMB 3.0 (2012): 2012 saw the release of SMB 3.0 in Windows Server and Windows 8. It made a number of noteworthy additions to enhance administration, security, backup, availability, and performance. SMB Multichannel, SMB Direct, transparent client access failover, support for Remote Volume Shadow Copy Service, SMB encryption, and other noteworthy new features were among them.
• SMB 3.02 (2014): Windows 8.1 and Windows Server 2012 R2 brought in SMB 3.02. Performance improvements and the option to turn off CIFS/SMB 1.0 support, together with the associated binaries' removal, were also added.
• SMB 3.1.1 (2015): SMB 3.1.1 was made available with Windows Server 2016 and Windows 10. Among other upgrades, it introduced support for cluster dialect fencing, pre-authentication integrity to thwart man-in-the-middle (MitM) attacks, and improved encryption.