Total Cookie Protection in Firefox

[ghost]

According to Mozilla, Total Cookie Protection in Firefox is enabled in Strict Mode. Does it even Work in Custom Mode ?

[rusty-snake]

Yes.

• If network.cookie.cookieBehavior (on about:config) is set to 5, TCP/dFPI is enabled (unless privacy.firstparty.isolate is set to true).
• network.cookie.cookieBehavior is set to different values depending on the ETP mode you use:
  • Standard: 4
  • Strict: 5
  • Custom:
    • Cross-site tracking cookies — includes social media cookies: 4
    • Cross-site cookies — includes social media cookies: 5
    • Cookies from unvisited websites: 3
    • All third-party cookies (may cause websites to break): 1
    • All cookies (will cause websites to break): 2

[ghost]

What you can is to block 3p cookies and use TC for isolation.

Could you Explain this in detail, because I can't follow it ?

[rusty-snake]

You can configure ETP to block 3p cookies and use TC to isolate cross site cookies (e.g. auto-mode + global isolation).

[ghost]

If I do use Strict mode in ETP does it also block all the things under Custom except Third Party Cookies.

[rusty-snake]

TL;DR: yes

• If you choose strict mode on about:preferences, you see a list of blocked things. Compare this to custom => yes
• If you unselected everything in custom, switch to strict and switch back to custom. Everything is selected => yes
• Search for browser.contentblocking.features.strict on about:config and see the selected features => yes
  • strict uses even more features because it enables the level 2 block list. If you want to enable the level 2 block list in custom mode, you need to set browser.contentblocking.customBlockList.preferences.ui.enabled=true first.
  • https://searchfox.org/mozilla-central/source/browser/app/profile/firefox.js#1755

[ghost]

Great to know, I think I have an answer.