syslog-ng is a syslogd replacement for a wide variety of UNIX systems that supports IPv6 and is capable of transferring log messages reliably using TCP and SSL and filtering the content of messages using regular expressions. Both RFC3164 and RFC5424 style messages are handled, but more esoteric formats like BSD process accounting logs are supported too. Apart from regular text files, it supports storing messages into SQL and MongoDB databases, and forward messages to local processes via pipes or UNIX domain sockets. This makes syslog-ng ideal as an integration platform. syslog-ng supports extracting structured information from the traditionally text based syslog via csv-parser(), db-parser(), and patterndb. Tag based classification, rewriting messages, and outputting messages in JSON is also possible. This makes syslog-ng ideal for preprocessing events for further analysis, be that home-grown scripts or SIEM systems. syslog-ng scales well on today's multi processor and multi-core systems: reaching 1,000,000 messages per second is a reality for the simplest use cases.
SysOrb is a client/server package that can monitor servers remotely (such as Web servers), or monitor devices on servers (such as disks, memory, load, etc.). It will alert the administrators via e-mail or pager if a server is entering a critical condition, and has its own database backend, allowing for massive collection of system statistics.
Tailbeep opens a file (-f), seeks to the end, and watches for a string (-s). If the string is found, a beep is sent to the specified tty (-t) device. You can also daemonize (-d) it. It was written to watch /var/log/messages for the DENY string (to catch anyone trying to break into a firewall), but you can use it to watch any open file that gets appended to. You can also create a log if you like, so you can record the events, in long or short mode. Tailbeep requires write access to one of the tty devices on the console.
TrinityOS is a step-by-step, example-driven HOWTO on building a very functional Linux box with strong security in mind. TrinityOS is well known for its strong packet firewall ruleset, Chrooted and Split DNS (v9 and v8), secured Sendmail (8.x), Linux PPTP, Serial consoles and Reverse TELNET, DHCPd, SSHd, UPSes, system performance tuning, the automated TrinityOS-Security implementation scripts, and much more.