NETBIOS

NETBIOS is a Protocole of transfer of file Co-developed by IBM and Sytec to the beginning of the year 1980. In 2005, it is used mainly by Microsoft. It is an interface which makes it possible to establish sessions between various computers of a network.

It uses the ports:

135 Service of localization used by the calls of remote procedure.
137 NETBIOS-NS - NETBIOS Name Service
138 NETBIOS-dgm - NETBIOS Datagram Service
139 NETBIOS-Sn - NETBIOS Session Service
445 (recent versions of Windows: 2000, XP, Vista)

For more information on the numbers of ports, to consult the article List of the software ports.

But NETBIOS in itself is not really a protocol, it is primarily a system of naming and a software interface.

History

In the beginning, it is IBM which combined NETBIOS with a protocol and carried out NetBEUI (NETBIOS Extended User Interface) in 1985.

NETBIOS Name Service (port UDP 137)

This service is used to associate a name of computer at an address IP.

This name is limited to 15 characters, plus a character informing about the type of machine: for example, with the graphical interface, one can have a field and a machine which bears the same name on 15 characters; in-house, the sixteenth character is allotted automatically and makes it possible to differentiate both.

NETBIOS Datagram Service (port UDP 138)

Description

This service makes it possible to exchange messages in mode off-line.

Heading of a package (in bytes)

NETBIOS Session Service (port TCP 139)

This service makes it possible to exchange messages in mode connected up to 131071 bytes.

Some useful orders

nbtstat - has nomnetbios: post the table corresponding to this name NETBIOS nbtstat - has ad.ip.de.mach: post the table corresponding at this address IP nbtstat - N: post the local table

nbtstat - R: post the table of the names solved by the WINS and broadcast

nmblookup - S: nomnetbios idem under Unix

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