Advisory Check is a program that reads security advisories for you. It gathers security advisories using RSS, RDF, or XML feeds, compares them against the installed software, and alerts you if you're vulnerable. A wide variety of package managers can be queried to detect installed software. Remote systems can be monitored by using the integrated SSH, Windows-RPC, and Nmap support.
Aranha is an application that uses an XML-RPC layer to retrieve information from one or more servers. The type of information gathered is implemented via plugins, and can be displayed or archived in several different ways. The data is gathered in Round Robin Databases (integrated with rrdtool) and can be accessed using a XUL interface available from the system. Plugins are very easy to write.
BigDaddy is a program for monitoring servers. It is similar to Nagios, with the added benefit of also monitoring and controlling the crontab (or any scheduled application) across an entire fleet of servers. The application comes in the form of a daemon for monitoring and reporting as well as an easy-to-use Web-based GUI for controlling monitoring, viewing timelines of incidents, filing incidents and graphing statistics. The application is extensible with any sort of monitoring module and notification is based on a five step escalation process.
BulkWatch is a utility that monitors sendmail's logs and takes a specified action when an IP has exceeded your configured maximum settings. You can specify that users may send X messages in X number of seconds. Email in excess of that would trigger an action, which can be any of the following: display an alert to the screen in foreground mode; log an alert to syslog; email an alert to a predefined email address; or run an external command with the IP and number of messages as arguments.
CaiCai is a network and services monitoring system. It performs tests for ping, DHCP, POP3, SMTP, FTP, etc. It does not require additional software installed on the remote side. It is fully configurable. It provides instant reports (via an HTML page), logs, statistics, and sound alarms.
CleverEye is an affordable availability monitoring suite for fundamental monitoring and reporting on network components, Web sites, databases, crucial user tasks, system health, and application transaction response times. It provides flexible, ready-made reports on real-time and historical system data for finding bottlenecks. Features include alerting, trend analysis, auto discovery, user management, network status map, SLA monitoring, and business level views.
Daemonzup is a server monitoring tool that will check if several services/daemons are up on a specific server. It is run from a cron job. If a daemon appears to be dead, it will send email to admins, plus it may also try to restart it. It is designed for GNU/Linux and depends on Perl. It can monitor whatever software is daemonized: apache, MySQL, SSH, cron, xinet, syslog, etc.