mon - 1.3.5-6 main

"mon" is a tool for monitoring the availability of services. Services
may be network-related, environmental conditions, or anything that can
be tested with software. If a service is unavailable mon can tell you
with syslog, email, your pager or a script of your choice. You can
control who gets each alert based on the time of day or day of week,
and you can control how often an existing problem is re-alerted.
.
More information can be found at http://mon.wiki.kernel.org