1. Install Squid Proxy:

   First, install Squid Proxy server:

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   sudo pacman -Syu squid
   

2. Configure Squid Proxy:

   Edit the Squid configuration file to configure URL filtering:

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   sudo nano /etc/squid/squid.conf
   

   Add or uncomment the following lines to enable URL filtering:

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   acl block_sites dstdomain "/etc/squid/block_sites.acl"
   http_access deny block_sites
   

   Save the changes and exit the editor.

3. Create Keyword List:

   Create a file containing keywords that you want to block:

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   sudo nano /etc/squid/block_sites.acl
   

   Add the keywords, each on a separate line:

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   .adult
   .porn
   .explicit
   

   Save the changes and exit the editor.

4. Update Permissions:

   Ensure that Squid has the necessary permissions to read the ACL file:

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   sudo chown -R proxy:proxy /etc/squid/block_sites.acl
   

5. Restart Squid:

   Restart the Squid service to apply the changes:

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   sudo systemctl restart squid
   

6. Test the Configuration:

   Test the configuration by attempting to access websites containing the specified keywords from a web browser. If the configuration is correct, access to these websites should be blocked.

To disable the keyword-based blocking, you can simply remove or comment out the relevant lines in the Squid configuration file (/etc/squid/squid.conf), restart the Squid service, and delete the keyword list file (/etc/squid/block_sites.acl).