quitTorrent

Relevant: http://www.reddit.com/r/apple/comments/kjtjo/does_there_exist_a_program_to_do_an_event_upon/

Scroll to bottom to copy text without line numbers.

File: ~/Library/Scripts/quitTorrent.com (You will likely have to create the Scripts folder)
-----START FILE HERE-------
#!/bin/bash

# Detect if I'm on campus' wifi.
# Quit Transmission so I don't anger them.

if [ `networksetup -getairportnetwork en1 | awk {'print $4'}` == "jefferson" ]; then
	killall Transmission
fi

exit 0
-----END FILE HERE-------

File: ~/Library/LaunchAgents/com.pheterson.quitTorrent.plist (Fill in your account)
-----START FILE HERE-------
<plist version="1.0">
<dict>
        <key>Label</key>
        <string>com.pheterson.quitTorrent</string>
        <key>ProgramArguments</key>
        <array>
                <string>/Users/**YOUR ACCOUNT**/Library/Scripts/quitTorrent.com</string>
        </array>
        <key>WatchPaths</key>
        <array>
        	<string>/Library/Preferences/SystemConfiguration</string>
        </array>
</dict>
</plist>
-----END FILE HERE-------