How To Block Specific Domains Using Squid Proxy Server

Squid is a powerful and flexible proxy server and web cache daemon. It can be used for various purposes, from speeding up web servers by caching repeated requests to filtering web content and blocking certain websites. In this article, we will focus on the latter and provide a step-by-step guide on how to block specific domains using Squid.

What is Squid?

Before diving into the instructions, let’s quickly touch on what Squid is. Squid is a proxy server that acts as an intermediary between a client and the internet. It provides the function of caching, which saves bandwidth and improves the speed of web browsing by serving cached content for repeated requests. Squid also supports a range of content filtering capabilities, one of which is blocking access to specific domains.

Why Block Specific Domains?

There are many reasons why one might want to block access to specific domains. These include improving network security, conserving bandwidth, enhancing productivity by blocking distractions, or enforcing company policies and compliance regulations.

Now, let’s move on to the main topic of this article: blocking specific domains using Squid. Follow the steps outlined below:

Step 1: Install Squid

First, you’ll need to have Squid installed on your system. The installation process varies depending on your operating system. On most Linux distributions, you can use the package manager to install Squid. For example, on Ubuntu, you can install Squid with the following command:

sudo apt-get update 
sudo apt-get install squid 

For CentOS, RHEL and Fedora, use:

sudo yum update 
sudo yum install squid 

Step 2: Backup Squid Configuration File

Before making any changes to the Squid configuration file, it’s a good practice to make a backup. This can be done with the following command:

sudo cp /etc/squid/squid.conf /etc/squid/squid.conf.bak 

Step 3: Create a Block List File

The next step is to create a file that contains the list of domains you want to block. You can create a file named blocked_domains.txt (or any name you prefer) in Squid’s configuration directory, usually /etc/squid.

sudo nano /etc/squid/blocked_domains.txt 

In this file, you list the domains that you want to block, one per line. For instance:

Step 4: Edit Squid’s Configuration File

Now you need to modify Squid’s configuration file to tell it to block the domains listed in your blocked_domains file. The main configuration file is usually named squid.conf and is also located in the /etc/squid directory.

Open the configuration file with a text editor. Then, add the following lines:

In the first line, `acl bad_domains dstdomain <filename>` creates an access control list (ACL) named `bad_domains` that matches destination domains. The path following it is the path to your blocklist file.

In the second line, `http_access deny bad_domains` denies access to the domains listed in the `bad_domains` ACL.

Step 5: Restart Squid Service

The last step is to restart Squid so that the new configuration takes effect. This can usually be done with the following command:

sudo systemctl restart squid 

Now, Squid should block access to the domains listed in your `blocked_domains` file.

Conclusion

In conclusion, Squid is a versatile tool that provides a range of capabilities, including the ability to block specific domains. With a simple blocked_domains file and a few lines in the configuration file, you can control what domains your users can access. Remember that the specific paths and commands may vary depending on your system, so be sure to consult your system’s or Squid’s documentation if you encounter any problems.

We hope you find this guide helpful in implementing your own domain-blocking rules using Squid. Happy surfing!