John the Ripper is a fast password cracker, currently available for many flavors of Unix, Windows, DOS, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. It supports several crypt(3) password hash types commonly found on Unix systems, as well as Windows LM hashes. On top of this, lots of other hashes and ciphers are added in the community-enhanced version (-jumbo), and some are added in John the Ripper Pro.
Dar is a shell command that makes backup of a directory tree and files. Its features include splitting archives over several files, DVD, CD, ZIP, or floppies, compression, full or differential backups, strong encryption, proper saving and restoration of hard links, extended attributes, file forks, Door inodes, and sparse files, remote backup using pipes and external commands (such as ssh), and rearrangement of the "slices" of an existing archive. It can run commands between slices, before and after saving some defined files or directories (for a proper database backup, for example), and quickly retrieve individual files from differential and full backups. Several external GUIs exist as alternatives to its CLI interface, like kdar, DarGUI, SaraB, etc.
The stunnel program is designed to work as an SSL encryption wrapper between remote client and local (inetd-startable) or remote server. It can be used to add SSL functionality to commonly used inetd daemons like POP2, POP3, and IMAP servers without any changes in the programs' code. It will negotiate an SSL connection using the OpenSSL or SSLeay libraries. It calls the underlying crypto libraries, so stunnel supports whatever cryptographic algorithms you compiled into your crypto package.
ZoneMinder is a suite of applications intended for use in video camera security applications, including theft prevention and child or family member monitoring. It supports capture, analysis, recording, and monitoring of video data coming from one or more video or network cameras attached to a Linux system. It also features a user-friendly Web interface which allows viewing, archival, review, and deletion of images and movies captured by the cameras. The image analysis system is highly configurable, permitting retention of specific events, while eliminating false positives. ZoneMinder supports both directly connected and network cameras and is built around the definition of a set of individual 'zones' of varying sensitivity and functionality for each camera. This allows the elimination of regions which should be ignored or the definition of areas which will alarm if various thresholds are exceeded in conjunction with other zones. All management, control, and other functions are supported through the Web interface.
Suricata is an Intrusion Detection and Prevention (IDS/IPS) engine developed by the Open Information Security Foundation and its supporting vendors. The engine is multi-threaded and has native IPv6 support, file extraction capabilities, and many more features. It's capable of loading existing Snort rules and signatures, and supports many frontends through Barnyard2.
OpenNetAdmin provides a database managed inventory of your IP network (IPAM). Each host can be tracked via a centralized AJAX-enabled Web interface that can help reduce tracking errors. It also has the ability to generate DHCP and DNS configuration for individual servers from the data stored in the database. There is a command line interface for batch scripting that can be accessed remotely or locally.
Xplico is an IP traffic decoder that extracts data from an Internet traffic capture. From a pcap file, it can extracts each email (POP, IMAP, and SMTP protocols), all HTTP content, VoIP calls (SIP, RTP, H323, MEGACO, MGCP), IRC, MSN, and so on. It isn't a packet sniffer or a network protocol analyzer, but rather an IP/Internet traffic decoder or network forensic analysis tool (NFAT).
Revelation is a full-featured and secure password manager for the GNOME 2 desktop. It aims to be user-friendly and HIG-compliant, and it is tightly integrated with GNOME. It has several account types which can be grouped in folders, searched, and opened in external applications. It can both test and generate passwords. Accounts are stored in an encrypted file which can be accessed remotely via SSH, FTP, HTTP, WebDAV, and more. It can import and export data files for Password Safe, GPass, Figaro's Password Manager, and others.
vlock is a program to lock one or more sessions on the Linux console. This is especially useful for Linux machines which have multiple users with access to the console. One user may lock his or her session(s) while still allowing other users to use the system on other virtual consoles. If desired, the entire console may be locked and virtual console switching disabled.