Tcp port 139. May 15, 2019 · That's what TCP port 445 is used for. Learn what runs on this port, security risks, and best practices. NetBIOS is a legacy protocol that provides name resolution, datagram, and session services. Port 139 is used by SMB dialects that communicate over NetBIOS. It is primarily used to enable applications and devices to access shared resources, such as files and printers residing on other networked devices, across a Windows-based LAN. Dec 25, 2025 · Port 139 is used for File and Printer Sharing but is the single most dangerous Port on the Internet. NetBIOS over TCP/IP (NetBT) utilizes this port to communicate. Jul 19, 2024 · Port 139 is the dedicated port for SMB over NetBIOS. Sep 27, 2024 · What are Port 139 and Port 445? For the SMB protocol to function correctly, network ports are required to communicate with other systems. For example, printers and serials ports communicate via Port 139. mizlael jvuo uxnxl sebag mhgm xmwhw hly hxhub nznskp epos