---
title: "Securing NETBIOS"
slug: "securing-netbios"
updated: 2026-04-13T06:52:11Z
published: 2026-04-13T06:52:11Z
canonical: "docs.serversaustralia.com.au/securing-netbios"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.serversaustralia.com.au/llms.txt
> Use this file to discover all available pages before exploring further.

# Securing NETBIOS

Following on from DNS Amplification DDOS attacks, more recently NETBIOS services are being utilised for "Amplification DDOS attacks" to reflect traffic against other networks. You can read up on this further at the below URL: [https://www.shadowserver.org/wiki/pmwiki.php/Services/Open-NetBIOS](https://www.shadowserver.org/wiki/pmwiki.php/Services/Open-NetBIOS)

The easiest way to resolve this issue, is by creating a Firewall rule, to block Port 137, for incoming traffic for UDP excluding trusted IP ranges. Below are some basic examples when testing, showing before, and after information using the **nbtstat** command in Windows CMD Prompt.

**Testing - Before**

![](https://cdn0.mysau.com.au/helpcenter_attachments/205216824/nbtstat1.PNG)

**Testing - After**

![](https://cdn0.mysau.com.au/helpcenter_attachments/205216824/nbtstat2.PNG)