A simple way of getting notified by email if one or more local network devices go offline for any reason.
This will scan any IP ranges specified in config.ini (see IpRangesToScan) and checks that any IPs mentioned in RequiredIps are online. If they aren't, it will send an email to the specified notification email.
This script is designed for Linux since it uses nmap, however it should run on a Windows OS as long as nmap is installed (https://nmap.org/book/inst-windows.html) and available on the PATH. I haven't tested this though.
The config.ini file is fairly basic: update the to/from notification name and email addresses as needed. Then there's just two IP address items: the IP ranges to scan (IpRangesToScan), and which IP(s) are should be required as online (RequiredIps).
IpRangesToScan is basically the list of IP subnets that you want to scan. If you have a single router and all your devices have IP addresses in the same range (e.g. 192.168.1.30 and 192.168.1.202) then you might just need to enter a single value here such as 192.168.1.0/24.
However if you have multiple Wi-Fi points (for example you run a mesh Wi-FI set-up), you might need to enter multiple values here. I have four Eero Pro 6 points and my devices connect over 192.168.4.*, 192.168.6.* and 192.168.7.* so that's why I have entered three IP ranges here.
This uses the Mailersend API to send emails (although naturally you can use your own provider or approach by modifying send_email_notification()).
The Mailersend API key can only be specified by an environment variable: MAILERSEND_API_KEY
So you can run this script by modifying config.ini as required, and then running something like:
MAILERSEND_API_KEY='changeme' python3 main.py
You can also change the logging level by adding a --loglevel param, for example by running:
MAILERSEND_API_KEY='changeme' python3 main.py --loglevel debug