How to Configure ACL http_status 403 in Squid-Cache

When using Squid-Cache as a web proxy server, you may encounter situations where you want to configure ACL http_status 403. This configuration allows you to customize the error message displayed when a user attempts to access a forbidden website. In this article, we will guide you through the process of configuring ACL http_status 403 in Squid-Cache.

Step 1: Understanding ACL and http_status

Before we dive into the configuration process, let's understand what ACL and http_status mean in Squid-Cache.

ACL (Access Control List): ACL is a feature in Squid-Cache that allows you to define rules to control access to certain resources. It can be used to block or allow specific websites, based on various criteria such as IP address, domain name, URL, etc.

http_status: http_status is a Squid-Cache directive that specifies the HTTP status code to be sent to the client when a certain condition is met. In our case, we will use http_status 403, which corresponds to the "Forbidden" status code.

Step 2: Editing the Squid Configuration File

To configure ACL http_status 403, you need to edit the Squid configuration file. The default location of this file is /etc/squid/squid.conf. Open the file using a text editor of your choice.

Find the section where ACL rules are defined. It typically looks like this:

In the above example, we have defined two ACL rules: localnet and blocked_sites. The localnet rule allows access from the local network (192.168.0.0/24), while the blocked_sites rule blocks access to any website with a domain name ending in .example.com.

Step 3: Adding http_status 403

Now, let's add the http_status 403 directive to the ACL rule that you want to apply it to. For example, if you want to display a custom error message when a user tries to access a blocked website, you can add the http_status 403 directive to the blocked_sites ACL rule.

In the above example, we have added the http_status 403 directive to the blocked_sites ACL rule. This means that when a user tries to access a website with a domain name ending in .example.com, Squid-Cache will deny the access and send a "Forbidden" error message to the user.

Step 4: Customizing the Error Message

By default, Squid-Cache displays a generic error message when http_status 403 is triggered. However, you can customize this error message to provide more specific information to the user.

To customize the error message, you need to create a custom HTML error page and specify its location in the Squid configuration file. Here's how you can do it:

In the above example, we have set the error_directory directive to /usr/share/squid/errors/, which is the location where Squid-Cache looks for error pages. We have also set the err_access_denied directive to my_custom_error.html, which is the name of our custom error page.

Create a new HTML file named my_custom_error.html in the specified directory (/usr/share/squid/errors/) and customize it according to your needs. You can include helpful information, contact details, or any other relevant content to assist the user.

Step 5: Restarting Squid-Cache

Once you have made the necessary changes to the Squid configuration file, save the file and restart the Squid-Cache service for the changes to take effect. You can do this by running the following command:

After the service has restarted, ACL http_status 403 will be configured in Squid-Cache, and the custom error message will be displayed when a user tries to access a forbidden website.

Congratulations! You have successfully configured ACL http_status 403 in Squid-Cache. Now, users will see a custom error message when they attempt to access blocked websites.

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