Picked up a Phomemo M08F recently and I really like it. It saves me heaps of time with simple stuff on the road like invoices etc… but I got curious about what the companion app was doing in the background. So I pointed my phone's DNS through a network level filter and just watched what the app looked up while I opened it and printed a page. If I am sending invoice info randomly over the web I sort of want to know.
The printing itself is all local over Bluetooth. The printer has no internet connection, so nothing actually has to leave your phone to make a page come out. The app is a different though and i'm sure there's workarounds but the app obviously works really well with the device.
I tested. In a single print it reached out to a whole stack of domains, including:
- An object storage bucket (the kind of endpoint you'd upload files to) that got contacted right when I hit print (??)
- A couple of Chinese cloud providers (Tencent and Alibaba), including a load balancer in a mainland China region (shock!)
- Umeng, which is a big mobile analytics SDK, on several domains
- A generic app analytics service
- A Facebook SDK endpoint
I can't tell you what was actually in any of that traffic. It might just be analytics and crash logs which would be meh. But an object storage endpoint firing every time you print is more than I'd expect from something whose only job is to burn dots onto a roll of paper, which it does well.
The good news is you can block all of it and printing still works fine, because the printing never needed the internet in the first place. I just added the app's phone home domains to a DNS blocklist. Any DNS sinkhole or Pi-hole style setup will do, and wildcard rules make it easy. Rough list of what I blocked:
qu-in.top qu-in.com tencentcs.com tencentclb.com umeng.com umengcloud.com dnse0.com app-analytics-services.com Not trying to start a panic, just sharing in case anyone else assumed a Bluetooth printer can't really send anything anywhere. Worth a look at your own DNS logs if you use one of these apps. Curious if anyone else sees the same M08F domains.
Happy printing!
Source: r/thermalprinting · by /u/RandemMandem