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Enable dynamic First-Party Isolation (dFPI)

Overview​

About this script

This script improves your privacy on Linux.

These changes use Linux system commands to update your settings.

Dynamic First-Party Isolation, also known as dFPI, is an advanced privacy feature in Firefox. This feature commonly referred to as:

  • Total Cookie Protection 1,
  • dFPI (dynamic First-Party Isolation) 2,
  • Dynamic storage partitioning 3.

Essentially, dFPI is an enhanced version of a previous privacy tool known as First-Party Isolation (FPI) 4.

The primary purpose of dFPI is to improve user privacy online. It accomplishes this by preventing third-party websites from accessing or tracking a user's data across different websites 1 3.

By default, this feature is activated for all Firefox desktop users 5.

Within Firefox's settings, there's an option called network.cookie.cookieBehavior which governs how dFPI operates. This setting has three potential values 3:

  • 5: The browser will block known trackers and partition storage for third-party content.
  • 4: Only known trackers will be blocked without any partitioning of third-party storage.
  • 0: All trackers and third-party content are allowed.

This script sets the value to 5, ensuring the highest level of privacy by blocking trackers and partitioning third-party storage. This aligns with recommended privacy practices because even if you choose the 4 value, the older First-Party Isolation (FPI) will still be active 6.

This script uses Bash (Shell script) scripting language.

Safe for General Use

This script is recommended for all users. It helps to improve privacy without affecting stability.

Implementation Details

  • Language: bash

  • Required Privileges: Root/sudo access

  • Compatibility: Linux only

  • Reversibility: Can be undone using provided revert script

Explore Categories​

This action belongs to Enable Firefox state partitioning (Total Cookie Protection) category. Web browsers, including Firefox, save various data types such as cookies, cache, and site-specific details. While this data helps in providing a faster and personalized browsing experience, it can be exploited by websites to track your activities across the internet, potentially compromising... Read more on category page ▶

Apply now​

Choose one of three ways to apply:

  1. Automatically via privacy.sexy: The easiest and safest option.
  2. Manually by downloading: Requires downloading a file.
  3. Manually by copying: Advanced flexibility.

Alternative 1. Apply with Privacy.sexy​

privacy.sexy is free and open-source application that lets securely apply this action easily.

Open privacy.sexy

You can fully restore this action (revert back to the original behavior) using the application.

privacy.sexy instructions
  1. Open or download the desktop application
  2. Search for the script name: Enable dynamic First-Party Isolation (dFPI).
  3. Check the script by clicking on the checkbox.
  4. Click on Run button at the bottom of the page.

Alternative 2. Download​

Irreversible Changes

This script is irreversible, meaning there is no straightforward method to restore changes once applied. Exercise caution before running, restoring it may not be possible.

  1. Download the script file by clicking on the button below:

    Download script

  2. Run the script file by clicking on it.

Download revert script​

This file restores your system to its original state, before this script is applied.

Download restore script

Alternative 3. Copy​

This is for advanced users. Consider automatically applying or downloading the script for simpler way.

  1. Open Terminal

  2. Copy the following code:

Code to apply changes
pref_name='network.cookie.cookieBehavior'
pref_value='5'
echo "Setting preference \"$pref_name\" to \"$pref_value\"."
declare -a profile_paths=(
  ~/.mozilla/firefox/*/
  ~/.var/app/org.mozilla.firefox/.mozilla/firefox/*/
  ~/snap/firefox/common/.mozilla/firefox/*/
)
declare -i total_profiles_found=0
for profile_dir in "${profile_paths[@]}"; do
  if [ ! -d "$profile_dir" ]; then
    continue
  fi
  if [[ ! "$(basename "$profile_dir")" =~ ^[a-z0-9]{8}\..+ ]]; then
    continue # Not a profile folder
  fi
  ((total_profiles_found++))
  user_js_file="${profile_dir}user.js"
  echo "$user_js_file:"
  if [ ! -f "$user_js_file" ]; then
    touch "$user_js_file"
    echo $'\t''Created new user.js file'
  fi
  pref_start="user_pref(\"$pref_name\","
  pref_line="user_pref(\"$pref_name\", $pref_value);"
  if ! grep --quiet "^$pref_start" "${user_js_file}"; then
    echo -n $'\n'"$pref_line" >> "$user_js_file"
    echo $'\t'"Successfully added a new preference in $user_js_file."
  elif grep --quiet "^$pref_line$" "$user_js_file"; then
    echo $'\t'"Skipping, preference is already set as expected in $user_js_file."
  else
    sed --in-place "/^$pref_start/c\\$pref_line" "$user_js_file"
    echo $'\t'"Successfully replaced the existing incorrect preference in $user_js_file."
  fi
done
if [ "$total_profiles_found" -eq 0 ]; then
  echo 'No profile folders are found, no changes are made.'
else
  echo "Successfully verified preferences in $total_profiles_found profiles."
fi
  1. Paste the code into terminal.
  2. Press Enter to apply the code.

Some scripts requires restarting your computer to take affect.

Copy restore code​

Copy and run the following code to restore changes:

Revert code
pref_name='network.cookie.cookieBehavior'
pref_value='5'
echo "Reverting preference: \"$pref_name\" to its default."
if command -v 'ps' &> /dev/null && ps aux | grep -i "[f]irefox" > /dev/null; then
  >&2 echo -e "\e[33mWarning: Firefox is currently running. Please close Firefox before executing the revert script to ensure changes are applied effectively.\e[0m"
fi
declare -a files_to_modify=('prefs.js' 'user.js')
declare -a profile_paths=(
  ~/.mozilla/firefox/*/
  ~/.var/app/org.mozilla.firefox/.mozilla/firefox/*/
  ~/snap/firefox/common/.mozilla/firefox/*/
)
declare -i total_profiles_found=0
for profile_dir in "${profile_paths[@]}"; do
  if [ ! -d "$profile_dir" ]; then
    continue
  fi
  if [[ ! "$(basename "$profile_dir")" =~ ^[a-z0-9]{8}\..+ ]]; then
    continue # Not a profile folder
  fi
  ((total_profiles_found++))
  for file_to_modify in "${files_to_modify[@]}"; do
    config_file_path="${profile_dir}${file_to_modify}"
    if [ ! -f "$config_file_path" ]; then
      continue
    fi
    echo "$config_file_path:"
    pref_start="user_pref(\"$pref_name\","
    pref_line="user_pref(\"$pref_name\", $pref_value);"
    if ! grep --quiet "^$pref_start" "${config_file_path}"; then
      echo $'\t''Skipping, preference was not configured before.'
    elif grep --quiet "^$pref_line$" "${config_file_path}"; then
      sed --in-place "/^$pref_line/d" "$config_file_path"
      echo $'\t''Successfully reverted preference to default.'
      if ! grep --quiet '[^[:space:]]' "$config_file_path"; then
        rm "$config_file_path"
        echo $'\t'"Removed the file as it became empty."
      fi
    else
      echo $'\t''Skipping, the preference has value that is not configured by privacy.sexy.'
    fi
  done
done
if [ "$total_profiles_found" -eq 0 ]; then
  echo 'No reversion was necessary.'
else
  echo "Successfully verified preferences in $total_profiles_found profiles."
fi

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