NETBIOS Datagram Service
NETBIOS-DGM (NetBIOS Datagram Service) on port 138 enables connectionless communication between networked devices. It is primarily used for broadcasting messages and supporting applications that require NetBIOS over IP networks. This service is essential for certain legacy systems and applications that rely on NetBIOS for network communication.
What is NETBIOS Datagram Service
NETBIOS-DGM (NetBIOS Datagram Service) on port 138 is a crucial component for enabling connectionless communication between devices on a network using the NetBIOS protocol. Unlike connection-oriented services, NETBIOS-DGM allows for the broadcasting of messages to multiple devices without establishing a direct connection, making it suitable for applications that require quick and efficient message dissemination.
Historically, NetBIOS was developed in the early 1980s to provide network communication services for IBM PC networks. Over time, it became a standard for various network operating systems, including Microsoft Windows. NETBIOS-DGM is one of the three main NetBIOS services, alongside NetBIOS Name Service (NBNS) and NetBIOS Session Service (NBSS).
In modern networks, NETBIOS-DGM is often used in environments where legacy systems and applications still rely on NetBIOS for communication. Despite the advent of more advanced protocols, NetBIOS remains relevant in certain scenarios, particularly in small to medium-sized networks and in specific industrial applications. However, its use has declined with the rise of more secure and efficient protocols like TCP/IP.
While NETBIOS-DGM provides essential functionality for certain applications, it also poses security risks. The service can be exploited for network reconnaissance and other malicious activities if not properly secured. Therefore, it is crucial to implement appropriate security measures, such as firewalls and access controls, to mitigate potential threats.
NETBIOS Datagram Service runs on TCP and UDP port 138 and is official IANA port.Security risk
If port 138 is open and the NETBIOS-DGM service is running, it can be exploited for network reconnaissance and other malicious activities. Attackers can use this service to gather information about networked devices and potentially launch further attacks. It is essential to secure this port with firewalls and access controls to mitigate these risks.
In our UFW tutorial you can follow instructions how you can configure UFW to close port 138. Use StackChanges to monitor if the NETBIOS Datagram Service port is closed and stays closed. StackChanges will send an alert if port 138 is open again.