Bobcares

WeSupport

Call Us! 1-800-383-5193
Call Us! 1-800-383-5193
Call Us! 1-800-383-5193

Need Help?

Emergency Response Time custom

Our experts have had an average response time of 11.06 minutes in March 2021 to fix urgent issues.

We will keep your servers stable, secure and fast at all times for one fixed price.

Disable NetBIOS and LLMNR Protocols in Windows Using GPO

by | Apr 13, 2021

Wondering how to disable NetBIOS and LLMNR Protocols in Windows Using GPO? We can help you.

The broadcast protocols NetBIOS over TCP/IP and LLMNR are used in most modern networks only for compatibility with legacy Windows versions.

However, both protocols are susceptible to spoofing and MITM attacks. For improving network security, we can disable these protocols on the domain network.

Here at Bobcares, we often get requests from our customers using Windows servers to disable both NetBIOS and LLMNR as a part of our Server Management Services.

Today let’s see the steps that our Support Techs follow to disable these protocols.

How to Disable NetBIOS and LLMNR Protocols in Windows Using GPO

NetBIOS and LLMNR protocols allow computers on the local network to find each other if the DNS server is unavailable.

LLMNR (UDP/5355, Link-Local Multicast Name Resolution) is used in all Windows versions starting from Vista and allows IPv6 and IPv4 clients to resolve the names of neighboring computers without using DNS server due to broadcast requests in the local L2 network segment.

NetBIOS over TCP/IP or NBT-NS (UDP/137,138;TCP/139) is a broadcast protocol being a predecessor of LLMNR and used in the local network to publish and search for resources.

They are needed in a workgroup environment. However, in a domain network, we can disable both of these protocols.

Disabling LLMNR on Windows Using GPO

We can disable the LLMNR protocol on a Windows computer locally via the registry using the following PowerShell commands:

New-Item "HKLM:\SOFTWARE\Policies\Microsoft\Windows NT" -Name DNSClient -Force
New-ItemProperty "HKLM:\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient" -Name EnableMultiCast -Value 0 -PropertyType DWORD -Force

Following are the steps to disable using Group Policy:

1. First, open the gpmc.msc, create a new GPO or edit an existing one that is applied to all workstations and servers.

2. Then go to Computer Configuration and take Administrative Templates.

4. From there, go to Network and take DNS Client.

3. After that, we need to enable Turn off smart multi-homed name resolution policy by changing its value to Enabled.

4. Wait while the GPO settings on clients are updated or manually update them using the following command:

gpupdate /force

Disabling NetBIOS over TCP/IP via Group Policy

There is no separate GPO option that allows disabling NetBIOS over TCP/IP for all network adapters in Group Policy Editor.

We can use the following PowerShell logon script to completely disable NetBIOS for all network adapters:

$regkey = "HKLM:SYSTEM\CurrentControlSet\services\NetBT\Parameters\Interfaces"
Get-ChildItem $regkey |foreach { Set-ItemProperty -Path "$regkey\$($_.pschildname)" -Name NetbiosOptions -Value 2 -Verbose}

We can save this code to disableNetbios.ps1 file, copy it to the GPO directory.

To run on clients via Computer Configuration we can do the following steps:

Go to Policies in the computer configuration

And take Windows Settings

From there go to Scripts

After that take Startup and go to PowerShell Scripts.

If our current PowerShell execution policy is blocking this script from running on Windows computers, we must sign the PS1 script or run it in bypass mode.

For this change to take effect, we have to enable/disable network adapters or restart the computer.

Then open a command prompt and run the following command in order to check that NetBIOS is disabled for the network adapters :

wmic nicconfig get caption,index,TcpipNetbiosOptions

[Need assistance? We can help you]

Conclusion

In short, we saw how our Support Engineers disable NetBIOS and LLMNR Protocols in Windows Using GPO for our customers.

PREVENT YOUR SERVER FROM CRASHING!

Never again lose customers to poor server speed! Let us help you.

Our server experts will monitor & maintain your server 24/7 so that it remains lightning fast and secure.

GET STARTED

var google_conversion_label = "owonCMyG5nEQ0aD71QM";

0 Comments

Submit a Comment

Your email address will not be published. Required fields are marked *

Privacy Preference Center

Necessary

Necessary cookies help make a website usable by enabling basic functions like page navigation and access to secure areas of the website. The website cannot function properly without these cookies.

PHPSESSID - Preserves user session state across page requests.

gdpr[consent_types] - Used to store user consents.

gdpr[allowed_cookies] - Used to store user allowed cookies.

PHPSESSID, gdpr[consent_types], gdpr[allowed_cookies]
PHPSESSID
WHMCSpKDlPzh2chML

Statistics

Statistic cookies help website owners to understand how visitors interact with websites by collecting and reporting information anonymously.

_ga - Preserves user session state across page requests.

_gat - Used by Google Analytics to throttle request rate

_gid - Registers a unique ID that is used to generate statistical data on how you use the website.

smartlookCookie - Used to collect user device and location information of the site visitors to improve the websites User Experience.

_ga, _gat, _gid
_ga, _gat, _gid
smartlookCookie

Marketing

Marketing cookies are used to track visitors across websites. The intention is to display ads that are relevant and engaging for the individual user and thereby more valuable for publishers and third party advertisers.

IDE - Used by Google DoubleClick to register and report the website user's actions after viewing or clicking one of the advertiser's ads with the purpose of measuring the efficacy of an ad and to present targeted ads to the user.

test_cookie - Used to check if the user's browser supports cookies.

1P_JAR - Google cookie. These cookies are used to collect website statistics and track conversion rates.

NID - Registers a unique ID that identifies a returning user's device. The ID is used for serving ads that are most relevant to the user.

DV - Google ad personalisation

IDE, test_cookie, 1P_JAR, NID, DV, NID
IDE, test_cookie
1P_JAR, NID, DV
NID
hblid

Security

These are essential site cookies, used by the google reCAPTCHA. These cookies use an unique identifier to verify if a visitor is human or a bot.

SID, APISID, HSID, NID, PREF
SID, APISID, HSID, NID, PREF