sawdog

Sawdog (Simple Active Watch-DOG) is a suite of scripts that informs the system operators of mission critical servers in the case of a failure. A set of small executables (i.e. expect scripts) are executed, and if one executable fails, it sends an email or an SMS to the sysop. There are 3 states known to sawdog: alive, unknown, and dead. Only certain state transitions trigger a notification. On a Web interface, the states of all hosts are visible. So far, there are scripts to check for DNS, FTP, HTTP, HTTPS, ICMP, IMAP, MS SQL, MySQL, Notes, NTP, POP3, PostgreSQL, SMB, SMTP, SNMP, SSH, telnet, TWS, VNM, and Webmin.