So what does Fido do? Well, to put it simply, Fido monitors IP addresses - routers, servers, whatever - by pinging to see if the connection is alive and the interface is responding. If it doesn't receive an answer to the ping, it logs the downtime, and optionally executes an X10 command to power-cycle the device that has gone down.

Now, you wouldn't normally want to power cycle a server simply because its interface has gone down, but that's not really what Fido is built to do. Fido was written several years ago, when my connection to the internet was a very flakey cable modem. Without fail, at least once in every 36 hour period, the cable modem would simply die. The only way to get it back online was to power cycle the modem - and so, Fido was born. I later added the multiple-device capability because I used it to monitor a WAN connection from one of my offices; there, the "X10 command" was forcibly changed to a one-liner that reset the VPN tunnel, unless the second interface (the true router to the Internet) was also down, in which case it simply logged the downtime and waited for the router to become available again.

Fido is available under the terms of the GPL license.

INSTALL file