In this article I will show you how to use the hosts file to block websites on computers running the Windows operating system. I will also go over the limitations of using the hosts file to restrict access to the web when compared to dedicated web filtering software so you can choose the best internet management method for your needs.
Editing the Hosts file to block a website on multiple devices is a time-consuming, inflexible, and labor-intensive process.
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|Hosts File||Web Filter|
|Multiple Devices||Not recommended. It forces you to decentralize the management of your network.||Recommended. The centralized console of a web filter makes managing multiple devices simple and efficient.|
|Granularity||Limited. Web access permissions can only be done on a per-device basis. Changes to the file also affects all users on the device.||Advanced. Unique web access permissions can be adjusted for each device, user, or workgroup.|
|Whitelisting||Difficult. Using the hosts file block all websites except approved ones requires you to manually find the IP addresses of the websites you would like to allow, add them to the file, and direct all other traffic to a null route.||Simple. To whitelist websites with a web filter you simply need to add the domains you’d like to allow to a whitelist (allow list) and all other domains will be blocked by default.|
|Wildcard Filtering||Not Supported. You need to specify each and every variation of a URL you would like to block.||Supported. A web filter allows you to block all URLs within a domain with one wildcard entry.|
|Ease of Use||Difficult. You have to edit the hosts manually for every single device you want to manage. You will also need to reconfigure the file every time you wipe the machine.||Simple. All you need to do is add the websites you’d like to block to your block list.|
Want to learn more? Check out our article on the benefits of web filters.
The hosts file in Windows is a text file that is used by the operating system to map hostnames to IP addresses. In Windows 10 it located in the System 32 folder at C:\Windows\System32\drivers\etc folder
Editing the hosts file in Windows lets you change the IP address that a given website resolves to on your computer. This allows you to override the destination that a website’s DNS zone file would normally take you to.
Since these changes only apply to your local machine this method of web filtering is useful for blocking websites on a personal device. However, anyone managing multiple devices should use a dedicated web content filter instead of blocking websites using hosts file to make policy updates more efficiently.
How you normally get access to web content
Normally when you enter a URL (such as Facebook.com) into the address bar of your web browser it will send a Domain Name System (DNS) request to a server. DNS changes the names of these human-readable domains into an IP address such as 18.104.22.168 (for IPv4) or 2a03:2880:f10e:83:face:b00c:0:25de (for IPv6) that identifies the server’s location.
How hosts changes this
You can think of DNS as the internet phone book and the hosts file of your local machine as your own personal address book.
Imagine you’re looking up someone’s phone number. Before resorting to the phone book (DNS) you’ll first take a look at your personal address book (the hosts file) to see if you have any contact details (IP addresses). If you do, you’ll not bother to check the phone book at all.
Your computer works the same way. Before any request for a domain takes place from your web browser, your machine will actually reference the local hosts file first. If any entries are found there they will be used instead.
This is precisely how you are able to block websites using hosts file. It has lines of text that consist of an IP address followed by a host name. These lines of text can be modified to tell your web browser that a given host name should route to a given IP address.
So, if you want to stop your users from accessing Facebook you can enter Facebook.com into your hosts file and route it to the IP address of your local machine (127.0.0.1). This will allow you to block websites using hosts file.
DNS changes names of domains into IP addresses. For example, 22.214.171.124 is one of the IPs of facebook.com. You can use a hosts file to change that and redirect the site you want to block to another address. It will allow you to link a certain domain name with any IP address you want.
Note: When you block websites using hosts file the websites will only be blocked on the local PC. To ensure that websites are blocked on multiple computers you need dedicated web filtering software.
Ad filtering with the hosts file works exactly the same way as blocking a website does. Entries for known malicious or spammy domains can be blocked by adding them to the file and redirecting them to another IP address.
Web developers can use the hosts file to test and develop websites on their local machine. To make changes to a website before it is made public the web developer will install the site files locally and edit the hosts file on their computer so that it points the sites domain name to the IP address of the environment they want to test in.
When a file is read-only you can freely open it but you can’t save any changes you make.
Follow these steps to disable read-only mode:
# Copyright (c) 1993-2009 Microsoft Corp.
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a ‘#’ symbol.
# For example:
# 126.96.36.199 rhino.acme.com # source server
# 188.8.131.52 x.acme.com # x client host
# localhost name resolution is handled within DNS itself.
# 127.0.0.1 localhost
# ::1 localhost
Note: All of the octothorpes (aka hashtag/pound sign/number symbol – #) are used to comment out text entries. Any content on the same line as the # symbol will be ignored. Thus, the default file does not actually do anything.
To access the hosts file using the file explorer you simply need to log in to an administrator account and enter %SystemRoot%\System32\drivers\etc\ into the address bar. If it is not there, it may be hidden. Follow this guide to show hidden files in Windows.
If you do not have administrator permission, you will receive an error like this:
Note: You must have administrator privileges to access and edit the hosts file. If you do not run Notepad under administrator privileges, you will only get to view the file and you will be unable to save your changes to the appropriate folder. Any changes you make will not work unless it is saved in the correct location – saving it in the Documents folder will not allow you to block websites using the hosts file.
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There are multiple ways to block users from accessing certain websites. Editing the hosts file in Windows is a viable method for blocking websites on a per-device basis, however to properly manage web filtering policies across multiple devices on a network you will need a centralized web filter.