A launchd daemon to execute a Python script when network configuration changes.

prehensile.networkwatcher.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
	"http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>Label</key>
	<string>prehensile.networkwatcher</string>
	<key>ProgramArguments</key>
	<array>
		<string>/usr/bin/python</string>
		<string>/Users/henry/Scripts/BigPicture.py</string>
	</array>
	<key>WatchPaths</key>
	<array>
		<string>/Library/Preferences/SystemConfiguration</string>
	</array>
</dict>
</plist>