what is NetBIOS Session ?

Question

My Anti Firewall apperars that with 217.218.196.4 TCP Port 49558

Answer 1

NetBIOS is an acronym for Network Basic Input/Output System. The NetBIOS API allows applications on separate computers to communicate over a local area network. It provides services related to the session layer of the OSI model.

NetBIOS was developed by Sytek Inc. for IBM 's PC-Network in 1983. The interface was designed for small networks; PC-Network only supported up to 80 devices in its baseband form. Since the interface was only originally published through a technical reference book from IBM, the protocol's API became a de facto standard....

Session mode lets two computers establish a connection for a "conversation," allows larger messages to be handled, and provides error detection and recovery. In NBT, the session service runs on TCP port 139.

The session service primitives offered by NetBIOS are:

* Call - opens a session to a remote NetBIOS name
* Listen - listen for attempts to open a session to a NetBIOS name
* Hang Up - close a session
* Send - sends a packet to the computer on the other end of a session
* Send No Ack - like Send, but doesn't require an acknowledgment
* Receive - wait for a packet to arrive from a Send on the other end of a session
...

Answer 2

NetBIOS is an older network protocol rarely used today because it is not routable, meaning it can not connect to the Internet or another computer network. It can only talk with one local network. It is probably not even being used on your PC and if you were to close that port it would not affect anything.