Hi all, I’ve gotten a Brother machine (DCP series) that can do wifi printing/scanning over their proprietary app. However, I’d like to lock it down from my network, because having it on the same LAN as my other devices and the ability to phone out to the internet seem like room for mischievious activities.

For context, I have OpenWRT on my router, and my clients can access the Brother using their iPrint&Scan app and AirPrint on wifi, as well as the traditional USB port. But I’m not good in networking. In my research, I drafted out the following solutions:

  1. Create a firewall rule to block the printer itself from making outbound requests. Seems simple, but I’m not sure if this can persist after IP changes or not.
  2. Create a VLAN for “IoT devices” that cannot send outbound requests to my normal VLAN nor the internet. Inspiration from this video, I’d need to manage a new SSID but it may come in handy for more IoT devices later.
  3. Hook the Brother up to a Raspberry Pi via USB, and install CUPS + SANE on the Pi. Assuming the Pi cannot “phone home” on behalf of the printer, this makes it a local-only “print+scan service” on my normal network and doesn’t require an extra VLAN.

I’d like to ask: which solution above is best for “neutering” the Brother? Or are there any alternatives/details I might’ve missed? I’m not sure if blocking outbound requests this way is enough of a security hardening for an untrusted device, and if there are any usability issues I’ve overlooked so far.

Thanks for any advice, and please share any printer/scanner setup you have in your networks as well. So hopefully I can get more inspiration!

  • jet@hackertalks.comEnglish
    0·
    22 hours ago

    Do your policy enforcement at the port level, connect the printer with a physical cable, that way even if the printer gets compromised and changes it’s Mac your rules still apply.

    Also setup your network alert system to notify you when a a new driver is available and the printer is behind so you can manually apply security updates.

    1 is fine from the port level

    2 is great, but more brittle

    2.5 only allow incoming connections to the vlan on printer ports, and outgoing mdns

    Depending on your threat model, you might need 3, if the printer is malicious, and printer drivers are also malicious, they can proxy information from the printer through a client device to the internet.