Nettest is a program which monitors a network connection, and takes some action (either email, audible notification, syslog entries, or all of the above) if/when the connection goes down.
You can download it from the following link: https://packetstormsecurity.com/files/download/12780/nettest-0.9.tar.gz
Source: https://packetstormsecurity.com/files/12780/nettest-0.9.tar.gz.html

