Devices show offline when they are online

[pchenriques]

Hi,
I have several devices that are always online but intermittently show as offline. I noticed this behaviour is applies in particular to higher device IP's in the range (the picture shows the Presence of an AP. Until June 14 it add the IP 192.168.1.72, and 192.168.1.241 after that date).

It's seems like the procedure to check online presence times out and doesn't reach the higher IP's. Is probably just a configuration setting. Any suggestions to fix the issue?
Thanks

[jokob-sk]

You can increase the time out on your scanners (e.g ARPSCAN_TIMEOUT from memory) or supplement your scans with additional scan methods (e.g ICMP scan) to make it more robust.

[slammingprogramming]

This is most likely. ARP alone is not entirely perfect. A mix of DNS/ARP/ICMP/etc. can significantly improve the accuracy of the presence reporting. Some devices, like iPhones, do not like being ARP scanned more than once per 15 minutes, and will sometimes still reject it if another device has done an ARP scan recently that "pinged" it. This is a security feature on Apple devices, just as an example. So I recommend taking the time to fine tune your ARP scans, but to also add other scanning functionalities to increase the reliability and accuracy of these reports and for down-detections and alerts.

[pchenriques]

@slammingprogramming , thanks for the feedback
I increased the ARPSCAN_TIMEOUT to 360s and implemented the ICNM scan for the home range IP's, as @jokob-sk suggested and it worked:

I'll keep looking into it to fine-tune the configuration.
Thanks to all!

[jokob-sk]

Thanks for the follow-up and glad it's resolved 🙂

[jokob-sk]

Added this guide to the docs: https://jokob-sk.github.io/NetAlertX/FIX_OFFLINE_DETECTION/

[pchenriques]

Added this guide to the docs: https://jokob-sk.github.io/NetAlertX/FIX_OFFLINE_DETECTION/

Great picture! Glad I could help... :-)