AIDE (Advanced Intrusion Detection Environment) is a file and directory integrity checker. It creates a database from the regular expression rules that it finds from the config file. Once this database is initialized it can be used to verify the integrity of the files. Several message digest algorithms are used. All of the usual file attributes can also be checked for inconsistencies.
di is a disk information utility that displays everything that df does and more. It features the ability to display your disk usage in whatever format you prefer. It also checks the user and group quotas, so that the user sees the space available for their use, not the system wide disk space. It is designed to be highly portable across many platforms and is great for heterogenous networks.
Passwd_exp notifies users via email of upcoming password or account expiration. Its simple modular architecture allows you to perform expiration checks on any data source you use (SQL databases, LDAP...), send expiration warnings only to desired users or group and on selected days only. Administrators can use it to review expired accounts in the system. Support for Linux and Solaris shadow (including LDAP and NIS systems) and BSD passwd systems is included.
klogview is a KDE real-time log file viewer, like tail -f. The main window contains any number of dockable log panels, with an arbitrary number of log sources in each of them. Every log source can have a separate font color and style. Other features include filters, alerts, different encodings, and tray support.
Band Saw is a syslog monitoring program for GNOME. It allows the user to define filters that specify which log messages should be drawn to the user's attention. Combined with syslog's remote logging functionality it provides an effective, scalable, and easily deployed monitoring solution.
OpenSMART is a monitoring (and reporting) environment for servers and applications in a network. Its main features are a nice Web front end, monitored servers requiring only a Perl installation, XML configuration, and good documentation. It is easy to write more checks. Supported platforms are Linux, HP/UX, Solaris, AIX, *BSD, and Windows (only as a client).
PHP System Administration Toolkit is a toolkit/framework for the rapid development of system and network administration Web interfaces in PHP. It tries to take as much common work from the developer as possible, and provides object-oriented interfaces to many common services. It aims to make the applications built using it easily customizable, extensible, and maintainable.
KProbe is an Asus notebook monitor for KDE. It is like the Asus PCProbe software for Windows, but with more options and tuning. It allows you to set the monitor brightness and CPU speed on the fly. It can check KMail via the DCOP interface to check if there are unread messages and enable the notebook's mail LED. It shows a graph and statistics about temperature. It has support for i18n, and English and Italian translations are available.