SMB stands for Server Message Block and is also known as Common Internet File System (CIFS).
It's the name for the communications protocol used by various operating systems produced by Microsoft over the years.
In computer networking, Server Message Block (SMB) operates as an application-layer network protocol mainly used for providing shared access to:
Present-day implementations often use TCP/IP as the underlying transports, previously NetBEUI was the transport.
Red Hat Linux supports SMB via the Samba server program.