• Peffse@lemmy.world
    link
    fedilink
    English
    arrow-up
    19
    ·
    4 days ago

    If you are using a network level block, make sure it’s a black hole and not just a DNS filter. I tried a DNS filter with a Roku and found that they bypass it with hardcoded values, even when the DNS server was statically assigned and DHCP assigned.

    • HumbleBragger@piefed.social
      link
      fedilink
      English
      arrow-up
      3
      ·
      4 days ago

      What you mean by black hole and filter? I blocked a bunch of tcl domains on my pihole and made my router drop everything in port 53 coming from every other device that wasn’t pihole. It seems to have worked for now… Is that a good solution?

      • matlag@sh.itjust.works
        link
        fedilink
        English
        arrow-up
        3
        ·
        3 days ago

        No, it’s not robust. It may work for your TV, but it can be worked around.

        DNS is like a phone directory for Internet: it translates domain name to IP addresses. If you block the DNS (what pihole does), it blocks the directory access. But if the IP address of the servers are hard-coded in the firmware, the TV does not need a DNS, it can reach the server directly.

        To trick the TV, you need to restrict the IPs it can reach. It might be delicate: it probably tries to ping some comme IPs to check it’s connected, then call the brand’s server for ads/updates/etc.

      • Bytemeister@lemmy.world
        link
        fedilink
        English
        arrow-up
        15
        ·
        4 days ago

        Pi-hole blocks the name resolution. TV wants to go to Hisense.com, asks your Pi-hole where that site is. Your Pi-hole sees that Hisense is on a block list, so it says back to your TV “sorry, no idea how to get to that site, it must be offline.”

        If the manufacturer wants to get around this, they program a public DNS in, like 8.8.8.8, or they hardcode the static IP for their website into the TV. Now when it wants to go to Hisense, it never has to ask your Pi-Hole where that site is, and it doesn’t get blocked. Heck, it probably won’t even show up on your Pi-hole’s logs.

        If you black hole the site, then any traffic going out there gets dropped, and the hard-coded addresses on the TV don’t matter for shit.