Microsoft-DS
The IANA-registered name for TCP port 445, used by Microsoft Directory Services for Server Message Block (SMB) over TCP. SMB on port 445 superseded the earlier NetBIOS over TCP/IP ...
The IANA-registered name for TCP port 445, used by Microsoft Directory Services for Server Message Block (SMB) over TCP. SMB on port 445 superseded the earlier NetBIOS over TCP/IP transport (ports 137 to 139) starting with Windows 2000. From a network security perspective, port 445 is one of the most-attacked ports on the internet because of the long history of remote SMB vulnerabilities (MS08-067, EternalBlue, and similar). Conventional security practice is to block inbound 445/tcp at the perimeter and restrict it inside the network to authorized hosts.