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.
mimic is a server that mimics Internet servers. It includes imitators for ftpd and telnetd, and can be extended with scripting to support other types of imitation. Users will believe they are connected to authentic services (such as ftpd or telnetd) but will never be able to log in. Everything that they type is logged. In addition, scripting new imitator services is simple. The program includes a one-liner example of a fully-functional echo server. The project's goal is to create a script for imitating most, if not all, popular Internet services.
ru is a reimplementation of the BSD 'rwhod' and 'ruptime' commands. It doesn't suffer from the performance impact of 'rwhod', scales to hundreds of servers, and supports a variety of platforms. In addition to the features provided by 'ruptime', it supports colorized output, availability reporting, graphing of system load averages using gnuplot, historical storage of system loading, and the grouping of servers.
Snoop is a GNU/Linux file descriptor monitoring tool inspired by FreeBSD's 'watch'. It goes beyond simple TTY snooping by allowing the interception of any file descriptor. You can attach on the fly to regular files, TTYs, named pipes, character devices, and pretty much anything that is represented by a file descriptor and addressable in the standard name space.
Libptytty is a small library that offers pseudo-TTY management in an OS-independent way. It was created out of frustration over the many differences of PTY/TTY handling in different operating systems for use inside "rxvt-unicode". It also offers session database support (utmp and optional wtmp/lastlog updates for login shells) and supports forking a proxy process after startup and dropping privileges in the calling process. It offers C++ and C-only APIs.