cross-posted from: https://lemmy.world/post/3754933

While experimenting with ProtonVPN’s Wireguard configs, I realized that my real IPv6 address was leaking while IPv4 was correctly going through the tunnel. How do I prevent this from happening?

I’ve already tried adding ::/0 to the AllowedIPs option and IPv6 is listed as disabled in the NetworkManager profile.

  • 30021190
    33•1 year ago

    The bad practise would be to entirely disable IPv6. #ShittySysAdmin

    • @empireOfLove@lemmy.oneEnglish
      24•1 year ago

      Broke: disabling ipv6 because it’s causing security holes with software not originally built for it

      Woke: disabling ipv6 because hex ip strings are too hard to type

    • @3laws@lemmy.world
      8•1 year ago

      The whole Silicon Valley, governments and economic infrastructure of the world hang by a thread made of bootleg shortcuts.

    • @Molecular0079@lemmy.worldOPEnglish
      6•1 year ago

      Haha, yeah that’s what ProtonVPN support recommended to me and I am not sure if I want to disable IPv6 globally like that. I feel (with my inexperienced brain) that there’s gotta be a way to do it on a per connection basis.

      • 30021190
        2•1 year ago

        Maybe try forcing only IPv4 connections for the traffic you want to keep private?

        Your biggest leak maybe IPv6 DNS which is probably not that big of a deal really…

    • @dack@lemmy.world
      2•1 year ago

      In this case, disabling IPv6 is actually the right move. If the VPN provider doesn’t support IPv6, then there’s no way to allow to allow IPv6 Internet traffic without causing a leak/VPN bypass. If you block IPv6 via firewall or routing it to a dead-end, it will add delays as things try IPv6, timeout, and fall back to IPv4. If you just remove the IPv6 address from the Internet interface, you have to also make sure it doesn’t get re-added by SLAAC/DHCPv6 or other interface changes (switching wifi networks, etc). As dumb as it seems, disabling IPv6 or switching to a provider that supports it are probably the best options.

      • @p1mrx@sh.itjust.works
        5•1 year ago

        In this case, disabling IPv6 is actually the right move. If the VPN provider doesn’t support IPv6, then there’s no way to allow to allow IPv6 Internet traffic without causing a leak/VPN bypass.

        The right move for the VPN provider is to support IPv6. The right move for the user is to take their business to a provider that does.

        • @dack@lemmy.world
          1•1 year ago

          Yes, I agree - using a VPN that supports IPv6 is preferred. If they don’t want to/can’t change providers, then disabling IPv6 is the best way to prevent IPv6 leaks without negatively affecting network performance.

    • @fuckwit_mcbumcrumble@lemmy.worldEnglish
      -1•1 year ago

      Unironically that’s one thing we do to anonymize traffic at work. We could do NAT via IPV6 but what’s the point when IPV4 already helps mask who is doing what in the office.

  • z3bra
    27•1 year ago

    IPv4 and IPv6 are two different network stacks. Your IPv4 stack is hidden behind wireguard, but not the IPv6 one.

    The correct way to fix your issue is to setup a second witeguard tunnel for IPv6, and route IPv6 traffic through it.

    Edit: many comments advise to block outbound IPv6 traffic. Don’t do that! It will add latency to all your requests as you will have to wait for them to timeout.

    • @notabot@lemm.ee
      2•1 year ago

      If you disable IPv6 at the kernel level there’s no extra latency as nothing even tries to connect to an IPv6 address. It’s a shame to have to do it, but does fix the issue.

      • z3bra
        1•1 year ago

        Disabling it is fine indeed, but I saw many comments advising to block outbound traffic, so I warned against that.

    • @Laser@feddit.de
      1•1 year ago

      For me, it was rather the opposite: when dropping IPv6 packets, applications would often hang and behave weirdly. Disabling IPv6 completely would mean they’d stop trying to do anything on IPv6 and function well.

  • dr_robot
    7•1 year ago

    Wireguard easily supports dual stack configuration on a single interface, but the VPN server must also have IPv6 enabled. I use AirVPN and I get both IPv6 and IPv4 with a single wireguard tunnel. In addition to the ::/0 route you also need a static IPv6 address for the wireguard interface. This address must be provided to you by ProtonVPN.

    If that’s not possible, the only solution is to entirely disable IPv6.

  • @nothacking@discuss.tchncs.de
    7•1 year ago

    The true enterprise solution is to disable IPv6, if you disable IPv4 you might be surprised to see how many sites and services, even those run by large companies require IPv4.

  • auth
    3•1 year ago

    I just disable ipv6 on my router to simply my firewall and such… Won’t use it until necessary

  • Presi300English
    2•1 year ago

    Just disable IPv6, if you don’t wanna, try a configuration tool like PiVPN, which can setup wireguard automatically

  • @wmassingham@lemmy.world
    2•1 year ago

    You can either route IPv6 through the tunnel, or if the tunnel doesn’t support it, you have to block it somehow if you don’t want it going out to the Internet. You can do that by creating a firewall rule to block it on your host or network, or by disabling IPv6 entirely at the host or network level.

    • @Molecular0079@lemmy.worldOPEnglish
      1•1 year ago

      You can either route IPv6 through the tunnel

      That’s what I am trying to do with the ::/0 option but it doesn’t seem to work. I am guessing because the tunnel itself doesn’t have IPv6?

      • Max-P
        1•1 year ago

        Add a dummy IPv6 on the WireGuard interface, like a completely random fd00::/128 address on it so it thinks it’s IPv6 enabled. It’ll then just go nowhere as the remote end won’t accept it. You can then drop it at the firewall level before it goes into the tunnel to save some bandwidth.

        • @Molecular0079@lemmy.worldOPEnglish
          3•1 year ago

          Thanks for the suggestion! It gave me the idea to try setting the connection profile’s IPv6 setting to either Link Local or Ignored. Both those options, along with the ::/0 in AllowedIPs, seem to work according to ipleak.net, but I am unsure what the bigger ramifications of this change are.

          • Max-P
            3•1 year ago

            It’s going to still send that IPv6 traffic through the tunnel and get discarded at the other end but that’s about it. You can firewall that off if you want, ideally with a reject rule so things don’t have to timeout before realizing it goes nowhere.