Groups > alt.comp.software.firefox > #17874

Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix

From	Brian Gregory <void-invalid-dead-dontuse@email.invalid>
Newsgroups	alt.comp.software.firefox, alt.os.linux, comp.mobile.android, alt.internet.wireless, alt.comp.os.windows-10
Subject	Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix
Date	2026-07-22 21:32 +0100
Organization	https://www.Brian-Gregory.me.uk/
Message-ID	<nccnmhF1b5nU1@mid.individual.net> (permalink)
References	<113kg6k$s72$1@nnrp.usenet.blueworldhosting.com>

Cross-posted to 5 groups.

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On 20/07/2026 07:45, Maria Sophia wrote:
> PSA:
> IPv6 browser privacy leaks are caused by the host, yet there's a fix.
>   ISP modem > IPv6-silent bridge > normal home router > Wi-Fi devices
> 
> On all platforms, web browsers can leak your globally-routable IPv6 address
> (even when you're using a VPN). This IPV6 privacy leak happens because the
> browsers prefer IPv6 and the OS host itself participates in IPv6 routing.
> 
> Basically, if the host has a global IPv6 address, a browser can expose it.
>    Browsers leak IPv6... but bridges stop it cold!
> 
> Specifically, a silent bridge is a bridge that passes IPv4 but never hands
> out or forwards IPv6, so no device behind it ever gets a global IPv6
> address. If the host never receives IPv6, the browser cannot leak IPv6.
> 
> Long story short, recently I delved into the *simplest* way to completely
> protect us (on any OS) from any web browser (Mozilla or Chromium) leaking
> IPV6 privacy (after recovering from a dreadful Windows IPV6 0xFF disaster).
>   Newsgroups: alt.comp.os.windows-10,alt.comp.microsoft.windows,alt.comp.os.windows-11
>   Subject: Have you ever disabled IPv6 for privacy (to prevent IP leaks)?
>   Date: Sat, 18 Jul 2026 12:47:22 -0400
>   Message-ID: <113gamq$ii0$1@nnrp.usenet.blueworldhosting.com>
> 
> There are lots of tricks, such as RFC 8981 IPV6 rotation privacy, but
> here's the important part I learned when I fully disabled IPv6 (0xFF)
> instead of only partially disabling it (0x20) as most people would do.
> 
> If a router is in bridge mode (no IPv6 delegation, no prefix assignment),
> all connected devices never receive a global IPv6 address.
>      *No global IPv6 address = nothing for the browser to leak.*
> 
> This protects IPV6 privacy on all operating systems and all web browsers.
>   a. It doesn't matter which browser you use (Chromium, Firefox, etc.).
>   b. It doesn't matter which OS you use.
>   c. If the host never receives an IPv6 address, the leak cannot occur.
> 
> IMHO, this is the simplest way to eliminate IPv6 browser leaks:
> Disable IPv6 at the router level by using a bridged configuration.
> 
> Host-level IPv6 participation is the root cause of IPV6 leaks.
> Hence, if we remove the host from IPv6 routing, that IPV6 leak disappears!
> 
> In summary, the topic of this PSA is likely not discussed anywhere else on
> this planet, but what I just learned was this simple IPv6 privacy epiphany.
>   1. Browsers leak IPv6 because they prefer IPv6 when available.
>   2. If the host receives a global IPv6 address (via SLAAC or DHCPv6),
>      the browser may expose it even if IPv4 traffic is tunneled thru VPN.
>   3. However, bridge mode prevents prefix delegation, so hosts never
>      obtain global IPv6 addresses.
> 
> No IPv6 address = no IPv6 leak!
> Who knew! Not me. Now I do!
> 
> As always, if you have a simpler solution, let's discuss it as the whole
> point of this thread is to ensure we can protect from IPv6 privacy leaks.

You are spouting a load of meaningless gibberish.
It sounds like you are basically disabling IPv6 but coming up with a 
load of complete rubbish to make it sound like you are doing something 
more clever. YOU ARE NOT DOING ANYTHING OTHER THAN DISABLING IPv6.

-- 
Brian Gregory (in England).

Thread

PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-20 02:45 -0400
  Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix "Carlos E. R." <robin_listas@es.invalid> - 2026-07-20 14:03 +0200
    Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 02:43 -0400
      Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix "Carlos E. R." <robin_listas@es.invalid> - 2026-07-21 11:18 +0200
        Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 07:36 -0400
          Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix "Carlos E. R." <robin_listas@es.invalid> - 2026-07-21 19:28 +0200
            Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 14:32 -0400
              Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Hank Rogers <Hank@nospam.invalid> - 2026-07-21 18:31 -0500
                Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-22 15:40 -0400
                Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-22 18:53 -0400
    Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Brian Gregory <void-invalid-dead-dontuse@email.invalid> - 2026-07-28 00:36 +0100
  Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix David Higton <dave@davehigton.me.uk> - 2026-07-20 20:47 +0100
    Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix "Carlos E. R." <robin_listas@es.invalid> - 2026-07-20 21:59 +0200
      Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 02:04 -0400
        Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix "Adam H. Kerman" <ahk@chinet.com> - 2026-07-21 06:37 +0000
          Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 03:23 -0400
        Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Nuno Silva <nunojsilva@invalid.invalid> - 2026-07-21 07:59 +0100
          Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 04:41 -0400
            Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix "Carlos E. R." <robin_listas@es.invalid> - 2026-07-21 11:03 +0200
              Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 05:47 -0400
                Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix "Carlos E. R." <robin_listas@es.invalid> - 2026-07-21 12:27 +0200
                Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 14:10 -0400
          Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix "Carlos E. R." <robin_listas@es.invalid> - 2026-07-21 10:53 +0200
            Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 05:19 -0400
              Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix "Carlos E. R." <robin_listas@es.invalid> - 2026-07-21 11:30 +0200
                Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 06:10 -0400
              Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-22 19:13 -0400
            Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Nuno Silva <nunojsilva@invalid.invalid> - 2026-07-22 09:47 +0100
              Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-22 16:30 -0400
      Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Brian Gregory <void-invalid-dead-dontuse@email.invalid> - 2026-07-22 21:35 +0100
        Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-22 16:46 -0400
          Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Brian Gregory <void-invalid-dead-dontuse@email.invalid> - 2026-07-23 04:33 +0100
            Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Nuno Silva <nunojsilva@invalid.invalid> - 2026-07-23 08:12 +0100
              Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-23 16:23 -0400
    Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Oregonian Haruspex <no_email@invalid.invalid> - 2026-07-25 04:58 +0000
      Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-26 14:25 -0700
  Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 01:38 -0400
    Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Nuno Silva <nunojsilva@invalid.invalid> - 2026-07-21 07:51 +0100
      Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-21 03:45 -0400
        Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Nuno Silva <nunojsilva@invalid.invalid> - 2026-07-22 09:37 +0100
          Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-24 11:36 -0700
  Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Brian Gregory <void-invalid-dead-dontuse@email.invalid> - 2026-07-22 21:32 +0100
    Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-22 16:54 -0400
      Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix agris <agris@invalid.tld> - 2026-07-22 17:05 -0700
        Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-22 23:06 -0400
          Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Brian Gregory <void-invalid-dead-dontuse@email.invalid> - 2026-07-23 04:50 +0100
            Re: PSA: IPv6 browser privacy leaks are caused by the host yet there's a simple fix Maria Sophia <mariasophia@comprehension.com> - 2026-07-23 16:51 -0400

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