Port :445SMB over Microsoft-DS

Port 445 is dedicated to Microsoft Directory Services utilizing SMB directly over TCP without the older NetBIOS layer. SMB (Server Message Block) protocol enables applications and users to access files, printers, and serial ports on a networked server, providing shared access necessary for seamless integration in Windows environments. Unlike classic SMB implementations that relied on NetBIOS over ports 137-139, modern SMB on port 445 operates natively over TCP/IP, improving efficiency and simplifying firewall rules.

This port underpins critical functions such as Active Directory operations, file sharing, printer sharing, and remote administration across Windows domains. SMB traffic over port 445 allows users to navigate network shares, map drives, and manage resources transparently. Since Windows 2000, Microsoft encouraged direct hosting of SMB on port 445 to phase out NetBIOS dependency, promoting a streamlined networking protocol stack.

Various SMB protocol versions (1.0, 2.0, 3.0+) are negotiated over port 445 depending on client and server capabilities. Later SMB versions introduce optimizations like faster performance, better resilience, and encryption support, enhancing functionality over this port. Though predominantly used on Windows, SMB implementations can also be found on Unix systems via projects like Samba.