NetBIOS

Network Basic Input/Output System, is an IBM standard protocol that operates on the Session layer and allows applications on different computers to communicate within a local area network.

This protocol provides three different services:

• Name Service (NetBIOS-NS): For name registration and resolution

• Datagram Service (NetBIOS-DGM): For connectionless communication

• Session Service (NetBIOS-SSN): For connection-oriented communication

Also, the NetBIOS operations use the following ports and protocols:

• Microsoft Remote Procedure Call (MS-RPC), which is an endpoint mapper used for client-to-client and server-to-client communication, on port 135

• NetBIOS Name Service, on UDP port 137

• NetBIOS Datagram Service, on UDP port 138

• NetBIOS Session Service, on port 139

• SMB protocol, used for sharing files between different operating systems, on port 445