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Firefox 76.0.1 seems to be ignoring the HOSTS file

islanderalmost
islanderalmost
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Windows 10, firefox 76.0.1

All of a sudden Firefox is serving up ads which used to be blocked by my HOSTS file.

Edge and Internet Explorer still seem to be using the HOSTS file OK.

Also, Firefox in a private window seems to use the HOSTS file.

I have deleted cookies and cache - no help.

Attached 3 screenshots, same site, banner Chevy ad with Firefox, hosts file blocks the Chevy ad in a Firefox private window and in Internet Explorer

Windows 10, firefox 76.0.1 All of a sudden Firefox is serving up ads which used to be blocked by my HOSTS file. Edge and Internet Explorer still seem to be using the HOSTS file OK. Also, Firefox in a private window seems to use the HOSTS file. I have deleted cookies and cache - no help. Attached 3 screenshots, same site, banner Chevy ad with Firefox, hosts file blocks the Chevy ad in a Firefox private window and in Internet Explorer
Attached screenshots

Chosen solution

islanderalmost said
But that begs the question: why does the private window not have the same problem ?

By default, Enhanced Tracking Protection settings are more stringent in private windows than regular windows. See: Enhanced Tracking Protection in Firefox for desktop.

Could that explain it?

Read this answer in context 👍 2

All Replies (4)

TyDraniu
TyDraniu
  • Top 10 Contributor
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  1. I think that the HOSTS file wasn't meant for ad blocking in Firefox. The usual way is to install an addon, for instance ublock origin.
  2. Probably it's because the DNS-over-HTTPS has been turned on. See Firefox DNS over HTTPS.
islanderalmost
islanderalmost Question owner
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Thanks for the info - yes, if I uncheck that box the ads go away.

But that begs the question: why does the private window not have the same problem ?

Also, I tried changing the HOSTS file entries from 0.0.0.0 to 127.0.0.1 - no help.

cor-el
cor-el
  • Moderator
  • Top 10 Contributor
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Some reading:

  • Bug 1453207 - Enabling DNS over HTTPS should respect system hosts file

(please do not comment in bug reports
https://bugzilla.mozilla.org/page.cgi?id=etiquette.html)

jscher2000 - Support Volunteer
jscher2000 - Support Volunteer
  • Top 10 Contributor
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Chosen Solution

islanderalmost said
But that begs the question: why does the private window not have the same problem ?

By default, Enhanced Tracking Protection settings are more stringent in private windows than regular windows. See: Enhanced Tracking Protection in Firefox for desktop.

Could that explain it?

Modified by jscher2000 - Support Volunteer