When Screensavers Go Rogue

Been struggling with some packet loss in the evenings here at the home QTH, so I lazily dropped my ISP, Kellin Communications, a note to see if they could see anything in their logs. An hour or so later (on New Years Eve, no less), my cell rings. It’s Kelly, the owner of Kellin.

Kelly knows I’m a retired network/security wonk so he opens straight out with “Do you realize you’ve used two terabytes this month?”


After apologizing profusely and promising to get to the bottom of this ASAFP, I rolled up my sleeves and fired up the Opnsense control panel. It didn’t take long in the Insight tool to find the smoking gun. had burned through 600G in the last 7 days alone! Well, that’s the new Mac Mini I recently built for the Mrs. WTF? I load up the Activity Monitor on her mac to see what the heck could be eating so much data and the culprit was right there, standing proud at the top of the list: Aerial.

Any Mac aficionado knows Aerial, the screensaver masterpiece by John Coates. Gorgeous high-definition, slo-mo flyovers of some of the most beautiful places on the planet. I’ve ran it for many years on my MacBook with no issues whatsoever so I never thought twice before installing it for the Mrs.

Thing is, in building her Mini, I also loaded up the latest OSX version, Catalina. Unfortunately, what I didn’t know until I googled “aerial bandwidth” last night was that Apple put severe restrictions on screensavers in Catalina. They now run sandboxed and don’t have disk access. This means Aerial cannot cache its video content locally. Instead of throwing up an error or warning however, Aerial happily continued along, direct streaming the videos constantly! 60-100G of HD video content, each and every day. Ooof.

Lesson here is, know your network. Know what “normal” traffic looks like for each device in your home so when things go sideways (and they will), it’ll be easy to see what changed. I only wish I’d have looked at my firewall first before calling Kellin. I should’ve known better.

BTW, if you call rural Colorado home and live in Kellin’s service area, give ’em a shot for your Internet needs. Best WISP by far (and I’ve dealt with several over  the years). Fair prices and they really know their stuff.