fireblock - Firefox Website Blocker for Linux

Overview

This script allows users to block or whitelist specific URLs or paths in Firefox by modifying the policies.json file.

Unlike traditional website blockers, it does not block entire domains by default, giving users fine-grained control over what is restricted.

Features

• Block specific URLs or paths in Firefox
• Add exceptions (whitelist URLs or paths)
• Prevent duplicate entries
• Works on a per-user basis (/usr/lib/firefox/distribution/policies.json)
• Can be adapted for system-wide policies

Prerequisites

This script requires jq, a lightweight JSON processor. Install it with:

sudo apt install jq  # Debian/Ubuntu
sudo dnf install jq  # Fedora
brew install jq      # macOS

Installation

1. Save the script as fireblock in /usr/local/bin/:

   sudo cp fireblock.sh /usr/local/bin/fireblock
   sudo chmod +x /usr/local/bin/fireblock

2. Ensure /usr/local/bin/ is in your $PATH (it usually is by default):

   export PATH="/usr/local/bin:$PATH"

Usage

Block Specific URLs or Paths

To block specific pages or paths on a website, run:

fireblock example.com another-site.com/specific-page

This adds only the specified URLs or paths to Firefox's blocked list.

Blocking Sub-paths or Entire Domains

If you want to block all sub-paths or an entire domain, add the * character at the end:

fireblock example.com/* another.com/pages/*

This ensures all pages under example.com are blocked and all sub-pages in another.com/pages are blocked.

Add Exceptions (Whitelist)

To allow specific sites or paths while others are blocked, use the -e flag:

fireblock -e example.com/specific-page

This adds example.com/specific-page to the exceptions list.

Editing Policies Manually

The policy file is located at:

/usr/lib/firefox/distribution/policies.json

For system-wide policies (root access required):

/etc/firefox/policies/policies.json

Notes

• Restart Firefox for changes to take effect.
• The script ensures no duplicate entries are added.
• For enterprise or system-wide settings, update the POLICY_FILE variable in the script accordingly.

References

• Customizing Firefox using policies.json
• Mozilla Policy Templates - Documentation