NETBIOS (NetBIOS Services Protocols)

NETBIOS protocol developed by IBM, the computer is mainly used for dozens of small local area network. The agreement is a program on the LAN can use the application programming interface (API), the program provides low-level service requests unified command set, the role is to provide a local area network and other special functions, the system can use the WINS services, broadcasting and Lmhost documents and other models will NetBIOS name resolution for the corresponding IP address, to achieve information and communication, so in the local area network using the NetBIOS protocol message communication can be easily achieved and resource sharing. Because it takes up less system resources, transmission efficiency is high, so are almost all local area network based on the NetBIOS protocol work.
NetBIOS defines a software interface and the media in the application and the connection between the communication interface to provide a standard method. NetBIOS is a session layer protocol, used in a variety of LAN (Ethernet, Token Ring, etc.) and WAN environment, such as TCP / IP, PPP, and X.25 networks.
 NetBIOS allows applications do not need to know, including error recovery (session mode), including network details.
NetBIOS request to the network control block (NCB: Network Control Block) in the form, NCB includes the location and target information is stored names and other information.
NetBIOS provides Open Systems Interconnection (OSI) model, the session layer and transport layer services, but does not support frames or data format standard transmission. NetBIOS Extended User Interface (NetBEUI) supports the standard frame format, which provides for the NetBIOS network layer and transport layer service support.
NetBIOS supports two communication modes: session (session) or datagram (datagram). Session mode is two computers to "talk" to establish a connection that allows processing large amounts of information, and error monitoring and recovery support. Datagram mode for the "no connection" (independent information transmission) operation, the information sent small error provided by the application monitoring and recovery. In addition the data also support the information reported mode broadcast to each computer on the LAN.
 NetBIOS name is 16 bytes long (if necessary filled with padding bits), the use of the byte value is almost no limit. For small networks do not perform routing, the NetBIOS name to IP address mapping in three ways:
1. IP broadcast - when the target address is not on the local cache, the broadcast NetBIOS name of the target computer that contains the data packets. Back to the IP address of the destination computer.
2. Lmhosts file - This is a responsible for mapping the IP address and the NetBIOS computer name of the file.
 3. NBNS - NetBIOS name server is responsible for the NetBIOS name to IP address mapping. The service by the Linux environment daemon (nmbd daemon) implementation