🦑 All About NetBIOS

🦑What is NetBIOS?

NetBIOS (Network Basic Input / Output System) is a protocol for working in local networks on personal computers such as IBM / PC, developed as an interface that is independent of the manufacturer. It was developed by Sytek Corporation by the order of IBM in 1983. It includes a session-level interface (Eng. NetBIOS interface), uses TCP and UDP as transport protocols.

🦑MORE DETAILS  :

1️⃣Applications can find through NETBIOS the resources they need, establish a connection, and send or receive information. NETBIOS uses port 137 for the name service, port 138 for the datagram service, and port 139. For sessions, any session begins with a NETBIOS request, specifying the IP address and determining the TCP port of the remote object, followed by the exchange of NETBIOS messages, after bringing the session to a close. The session exchanges information between two NETBIOS applications. 
2️⃣The message length ranges from 0 to 131071 bytes. The simultaneous establishment of several sessions between two objects is acceptable. When organizing IP transport via NETBIOS, the IP datagram is embedded in the NETBIOS packet. Information exchange occurs in this case without establishing a connection between the objects. NETBIOS names must contain IP addresses. 
3️⃣So, part of the NETBIOS address can be of the form IP. . . . , where IP indicates the type of operation (IP via Netbios), and . . .  is the IP address. NETBIOS system has its own system of commands (call, listen, hang up, send, receive, session status, reset, cancel, adapter status, unlink, remote program load) and primitives for working with datagrams (send a datagram, send a broadcast datagram, receive datagram, receive broadcast datagram). All NETBIOS end nodes are divided into three types:
1) Broadcast (“b”) nodes
2) point-to-point nodes (“p”);
3) nodes of the mixed type ("m").
4) An IP address can be associated with one of these types. B-nodes communicate with their partner through broadcast requests. P and M nodes use NetBIOS name server (NBNS) and datagram distribution server (NBDD) for this purpose.

🦑NetBIOS provides:

1) registration and verification of network names;
2) establishing and breaking connections;
3) communication with the confirmation of the delivery of information;
4) communication without confirmation of delivery of information;
5) support for managing and monitoring the driver and network card.