Good Morning from my Robotics Lab! This is Shadow_8472 with another short update my progress with my OPNsense firewall. Let’s get started.
I have done a substantial amount of work with DNS on my home network, but as noted in a previous post, it’s sub-optimal to exclusively manipulate your Domain Name System access from a power-hungry desktop when you sometimes have to ration electricity in your Uninterruptible Power Supply (UPS). I like PiHole’s web interface with all its fancy, moving graphs and charts, but our new firewall, Cerberus, can replicate the functionality I need.
I primarily use PiHole for DNS ad blocking, but I also explicitly blacklist a few URL’s while hosting local DNS records for servers on my Local Area Network (LAN), though the later is a work in progress.
OPNsense→Services→Unbound DNS→Blocklist→Type of DNSBL offers a drop-down checkbox menu of block lists. This is in contrast to PiHole→Adlists, which lets you import lists from arbitrary sources (edit the day after posting: OPNsense Unbound does have a URLs of Blocklists field). Either way, it should go without saying that sites and ads only need to be blocked once; it will only slow your DNS service down if given a bunch of redundant lists. From what I remember installing OISD Big onto PiHole, they aggregate several of these lists and remove the duplicates. PiHole also picked up a list named StephenBlack with a comment, “Migrated from /etc/pihole/adlists.list.” It sounds like a system default, but in any case, I found it had stuff not on OISD Big. OPNsense Unbound has the option for it, so it got migrated.
Migrating singled-out blacklist items was as simple as adding each entry to a comma-separated list (where PiHole wants separate entries). I’m going to wait on migrating my LAN domain names though. I believe I found the place to do it, but ButtonMash isn’t running Caddy to recognize subdomain requests right now.
One last step was to get into the red gaming router we’ve been using and point its DNS at Cerberus the Firewall. I then pointed its secondary DNS alternative at ButonMash.
To summarize, we should have the exact same protection as before on a smaller battery footprint and within the firewall’s default attack surface to boot!
Encrypted DNS
One of my eventual goals is to have my own recursive DNS server, which seeks out an a URL’s authoritative DNS record if it doesn’t have it cached. This will increase privacy, but I haven’t figured it out at a production grade yet. Instead, I looked up the best free and privacy respecting DNS, and so far as I can tell, that’s Cloudflare at 1.1.1.1.
From OPNsense, it wasn’t much more trouble to encrypt using DNS over TLS. I would prefer DNS over HTTPS, does the same thing but camouflages DNS requests as normal web traffic. For now, I’m assuming Unbound can’t do this and working properly. Please tell me if I’m wrong.
Takeaway
It’s slow going, but I am moving into Cerberus. While looking around, I found a module for NUT (Network UPS Tools), a utility for shutting down computers gracefully as their UPS runs down. I wanted to get it working, and for a moment after a reboot I did, but for reasons beyond me besides the driver on BSD not agreeing the best with CyberPower UPS systems, I’m at a loss. At this point, I am thinking to install a small Linux box to do the job at a future date, even though that will be yet another thing on the UPS.
Final Question
From above: Do you know of a way for OPNsense’s Unbound module to run DNS over HTTPS? I look forward to hearing from you in the comments below or on my Socials!