Half serious question. I’ve got 9 ESP32 nodes in a depot (temperature, door contacts, a couple of current clamps) talking to Hermetry over MQTT/TLS. Someone on our team read an article about IoT devices being fingerprinted by ISPs and attackers from traffic patterns, and now suggests we put a Tor router between the depot Wi-Fi and the internet so “nobody can see what the devices are doing”.
My gut says this makes things worse not better, but I can’t explain why beyond “it feels wrong”. The traffic is already TLS 1.2. What’s the actual risk model here, and is there something better I should do instead if the boss wants “more security”?
Wouldn’t Tor slow everything down a lot? We tried a VPN in our hotel and the door sensors got laggy.
Tor hides who you are talking to right? so if someone is watching the depot line they wouldn’t know you use Hermetry. isn’t that good?
It hides the destination from someone watching the depot line, yes, Rahul. But the destination was never the secret, and Tor costs you real things on the Hermetry side.
What actually protects you today: the MQTT session is TLS 1.2 minimum with forward-secret suites, so contents and the device token aren’t readable on the wire. Someone sniffing the depot uplink learns there’s a device talking to a broker every N seconds. Tor hides the broker name and adds a lot of latency and connection churn.
Now the costs. Every Tor circuit exits from a different address. Hermetry sends your admins a notice when a device logs in from a new network (at most once an hour per device), so 9 nodes hopping exits means a steady stream of those, and you train people to ignore exactly the warning that would tell them a token was stolen. You also lose the profile’s Allowed networks option, which is one of the best controls you have for fixed-site devices: list the depot’s public address and a stolen token used from anywhere else gets CONNACK 5. Plus repeated failed logins block an address for every device behind it, and on shared exits that’s not under your control.
If the boss wants more, I’d do this instead, all on the device profile:
- Allowed networks: the depot’s public IP
- TLS only, Token in the URL off, Commands allowed without TLS empty
- move from access tokens to X.509 if your firmware can, otherwise MQTT basic, one credential per device
- lower the profile Limits to what the nodes really send so a hijacked one gets cut off fast
And put the ESP32s on their own VLAN so a compromised node can’t reach the office PCs. Checklist is on Device transport security.
That’s the argument I couldn’t make. The new-network notices alone kill the Tor idea. Set Allowed networks to our static IP this afternoon, tested with a node on my phone hotspot and it got refused, Log tab showed the reason. Boss is happy, nobody installs Tor.
Didn’t know about Allowed networks, adding it to our hotel profile too.
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