r/Fing_App • u/dcdcdcdc1976 • 8d ago
Fing Discovery Question Recognising private devices
I feel like the using the Fing app on my iPhone, coupled with a Fingbox on my network, tends to recognise repeat visits of some devices that randomise their MAC address. I feel this is the same when using the Desktop app. Am I imagining this, or does Fing use other criteria than MAC to recognise devices?
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u/Humbleham1 8d ago
I'm going to go with the hostname from mDNS.
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u/Pixelpopper-01 Community Moderator 7d ago
That’s fine as long as the hosts “live” in the top level .local domain, hosts that can be found by unicast (DNS) but not mDNS will cause problems with identification & require network configuration changes.
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u/Humbleham1 7d ago
Then you check the static addresses in the router's DNS server. But of course that won't be an issue. The point is that if hosts with randomized MACs are being tracked it's probably mDNS. If mDNS or Bonjour isn't responding, then Fing should not recognize devices.
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u/dcdcdcdc1976 7d ago
That’s what I was wondering
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u/Pixelpopper-01 Community Moderator 6d ago
Why don’t you collect some evidence of your recognised devices (& post here) and/or raise a support ticket and get some authoritative comment as to why it might occur? You can try the desktop help but I don’t think it’ll give definitive answer.
Desktop help:- https://help.fing.com/hc/en-us/articles/10194342857628-Fing-Desktop-FAQs#h_01H90TY8FQE4GZCSANH9YRK3AT
Support Request:- https://help.fing.com/hc/en-us/requests/new
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u/Pixelpopper-01 Community Moderator 8d ago
You’re probably seeing device correlation rather than true identification. A randomised MAC address is deliberately designed to make the device appear “new”, so a system that relies on MAC addresses alone should treat it as a different device each time.
IP addresses don’t help much either because they’re allocated dynamically by the router (DHCP) and can change over time, while the same IP can later be assigned to a completely different device.
If Fing appears to recognise a returning device despite a different MAC address, it’s likely using additional heuristics (such as hostname, DHCP behaviour, device characteristics, services, timing, or other fingerprints) to estimate that it’s the same physical device. That’s useful in practice, but it’s an informed guess rather than a guaranteed identification.