What is the SMB Protocol? Even if you haven’t heard of the SMB protocol, millions of people use it every day. The Server Message Block (SMB) is a network protocol that enables users to communicate with remote computers and servers — to use their resources or share, open, and edit files. It’s also referred to as the server/client protocol, as the server has a resource that it can share with the client. Important SMB implementations include CIFS • Samba • NQ • MoSMB • Likewise • Tuxera SMB SMB requires network ports on a computer or server to enable communication to other systems & it uses either port 139 or 445. Port 139 • SMB originally ran on top of NetBIOS using port 139. NetBIOS is an older transport layer that allows Windows computers to talk to each other on the same network. Port 445 • Later versions of SMB (after Windows 2000) began to use port 445 on top of a TCP stack. Using TCP allows SMB to work over the internet.
On a TCP/IP network every device must have an IP address. However an IP address alone is not sufficient for running network applications, as a computer can run multiple applications and/or services. Just as the IP address identifies the computer, The network port identifies the application or service running on the computer. • Analogy If you use a house or apartment block analogy the IP address corresponds to the street address. All of the apartments share the same street address. However each apartment also has an apartment number which corresponds to the Port number.
