Buttons can monitor almost anything. It has built-in ability to chat with either a modem or a TCP socket. It can run external programs and flag a failure if the program returns a nonzero exit status.
Buttons can be variably sensitive to failures.
It can raise an alarm if a service fails to respond any number of times, and can cancel that alarm if a service resumes responding any other number of times. This number may be different for each service, but defaults can be set. One noteworthy part of Buttons is the remote control system. This license applies to the 971215 release. You acknowledge that the Buttons software may not be free from defects and that Jonathan H. Pickard, its author, has the right, but not the obligation, to repair such defects or enhance the Buttons software, with or without notice.