Let’s consider some ways to block access to the specific websites, domain names, URLs or IP addresses in Windows without using third-party tools. In our case, we will try to block certain websites using the built-in Windows 10 tools and PowerShell automation features.

Blocking Websites Using the Hosts File in Windows

The most popular method to block a specific website on Windows is to edit the hosts file. Usually it is located in %windir%\system32\drivers\etc\ directory. Please note that hosts file does not have an extension.

The path to the directory containing hosts file is set in the DataBasePath parameter under the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters. By default it is %SystemRoot%\System32\drivers\etc.

The hosts file is used to manually assign mappings between IP addresses and DNS names. When resolving names, the hosts has higher priority than DNS servers specified in the network connection settings.

To block a specific website (for example, facebook.com), open the hosts file (with the administrator privileges) and add the strings like these to it:

127.0.0.1 facebook.com
127.0.0.1 www.facebook.com

Save the file and restart your computer (or clear the DNS cache using the command: ipconfig /flushdns).

After that, when trying to open the facebook.com in any browser you will see the message “Page not found” / “Page not available”.

You can add new lines containing website URLs to your hosts file using such a .bat file:

@echo off
set hostspath=%windir%\System32\drivers\etc\hosts
echo 127.0.0.1 www.facebook.com >> %hostspath%
echo 127.0.0.1 facebook.com >> %hostspath%
exit

Or you can use the following PowerShell functions to automatically block specific websites in your hosts file.

Function BlockSiteHosts ( [Parameter(Mandatory=$true)]$Url) {
$hosts = 'C:\Windows\System32\drivers\etc\hosts'
$is_blocked = Get-Content -Path $hosts |
Select-String -Pattern ([regex]::Escape($Url))
If(-not $is_blocked) {
$hoststr="127.0.0.1 ” + $Url
Add-Content -Path $hosts -Value $hoststr
}
}

Function UnBlockSiteHosts ( [Parameter(Mandatory=$true)]$Url) {
$hosts = 'C:\Windows\System32\drivers\etc\hosts'
$is_blocked = Get-Content -Path $hosts |
Select-String -Pattern ([regex]::Escape($Url))
If($is_blocked) {
$newhosts = Get-Content -Path $hosts |
Where-Object {
$_ -notmatch ([regex]::Escape($Url))
}
Set-Content -Path $hosts -Value $newhosts
}
}

To add a website to the list of blocked URLs, just execute the command:

BlockSiteHosts ("twitter.com")

To unblock the website, run:

UnBlockSiteHosts ("twitter.com")

Block Websites Using DNS Filtering

If your clients use the same DNS server, in the same way you can block certain websites by creating a DNS entry in that DNS and specify something like 127.0.0.1 in it. By the way, most commercial DNS content filters (OpenDNS, SafeDNS, Cisco Umbrella, etc.) use the same principle.

How to Block Website IP Address in Windows Defender Firewall?

Also, you can block some websites using the built-in Windows Defender Firewall. The main disadvantage of this method is that you won’t be able to use the name of a domain or a website URL in the blocking rule. Windows Defender Firewall allows you to specify only an IP address or a subnet as a source/destination.
First of all, you have to get the IP address of the website you want to block. It is easier to do it using the nslookup command:

nslookup twitter.com

As you can see, the command has returned several IP addresses assigned to the website. You have to block all of them.

Run the Windows Defender Firewall management snap-in (Control Panel\All Control Panel Items\Windows Defender Firewall\Advanced Settings or by running firewall.cpl).

In the Outbound Rules section, create a new rule with the following settings:

• Rule Type: Custom
• Program: All programs
• Protocol Type: Any
• Scope: In the “Which remote IP addresses does this rule apply to?” section select “These IP addresses” -> Add. In the next window, enter the IP addresses, subnets or a range of IP addresses you want to block.

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