Qmrtg is a modular tool to help monitoring the activity of software processes. It's intended to be used with MRTG. It was originally written for monitoring qmail servers, but its modules are general enough to parse any kind of log file passed through multilog (see daemontools). QMRTG is modular. Each module carries out a different log analysis. A super-module lets the user easily request any analysis without having to know anything about the modules themselves. QMRTG is a modern alternative to qmailmrtg7.
Sshguard monitors services through their logging activity. It reacts to messages about dangerous activity by blocking the source address with the local firewall. Sshguard employs a clever parser that can transparently recognize several logging formats at once (syslog, syslog-ng, metalog, multilog, raw messages), and detects attacks for many services out of the box, including SSH, several ftpds, and dovecot. It can operate all the major firewalling systems, and features support for IPv6, whitelisting, suspension, and log message authentication.
SimCList is a high quality C library (that is C++ embeddable) for handling lists. It exploits several advanced techniques for improving performance, including freelists, sentinels, automatic sort algorithm selection, sort randomization, mid pointer, and optional multithreading. The API is simple but powerful, makes elegant and consistent use of information hiding, abstracts the actual data type to store, and is fairly complete. The library itself makes a good compromise between performance in terms of time and space, and is well documented.
Greylite is a SPAM filter with exceptional effectiveness and without false positives. It combines natively with qmail and works as a proxy for any SMTP server. It implements a modified greylisting algorithm that improves the filtering effectiveness and minimizes the delay drawbacks associated with the standard greylisting algorithm. It is self-contained because it uses SQLite, and is easy to setup and maintain, small, and fast.
@jone501: instead of bitching and thumbing down, consider being a good F/OSS citizen and report your problems to the project. pcsc-lite is _the_ toolkit for RFID and SmartCards under UNIX. This is remarkable and we should be grateful to Ludovic for his 7-years-long commitment.
Re: about qmail
DJB has strange ideas about itself and about how programs should intrude the system. Keeping the whole qmail "package" (including binary) in /var/qmail/ could be understood for non-intrusiveness, but what about keeping djbdns caches under /etc/? That quite frequent in DJB's software.
However, qmail is a great software and it really more simple to use than how most people think.
It' objectively much better than sendmail. It could be, instead, compared with courier and such.