---
description: Network Basic Input/Output System
---

# NetBIOS

## What is NetBIOS?

NetBIOS allows applications on different systems to communicate with one another over the LAN. It is used for:

* Sharing printers and files
* Remote procedure calls
* Exchange messages
* ...

If NetBIOS is not properly configured, it can leak:

* Computer names
* Usernames
* Domains
* Printers
* Available shares
* ...

## NetBIOS Enumeration

NetBIOS uses the following ports:

* **UDP 137: name services**
* **UDP 138: datagram services**
* **TCP 139: session services**





## Reference

{% embed url="https://book.hacktricks.xyz/pentesting/137-138-139-pentesting-netbios" %}
Pentesting NetBios - HackTricks
{% endembed %}
