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.
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.
Simple Groupware is a complete enterprise application offering email, calendaring, contacts, tasks, document management, synchronization with cell phones and Outlook, full-text search, and much more. Simple Groupware combines standards like RSS, iCalendar, vCard, IMAP, POP3, SMTP, CIFS, CSV, WebDAV, LDAP, and SyncML under one platform. Unlike other groupware software, Simple Groupware contains the programming language sgsML to enable the quick customization and creation of powerful Web applications.
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.
NetXMS is a network monitoring and management system with a modular architecture. It can be used for monitoring an entire IT infrastructure, starting with SNMP-capable hardware (like switches and routers) and ending with applications on servers. The system has a three-tier architecture; the information is collected by monitoring agents (either its own agents or SNMP agents) and delivered to the monitoring server for processing and storing, where it can be accessed by using the management console. It features centralized configuration and centralized agent upgrades.
The GNU Gatekeeper is a free H.323 gatekeeper based on the OpenH323 project. You can use it to manage a Voice-over-IP network and let endpoints (e.g., Netmeeting) communicate through symbolic names. It also has an external interface for billing and other applications. It runs on a number of Unix versions (including Linux and Solaris) and Windows.
PDFtk Server is a simple commandline tool for doing everyday things with PDF documents. You can use it to merge PDF documents or collate PDF page scans, split PDF pages into a new document, rotate PDF documents or pages, decrypt input as necessary (password required), encrypt output as desired, fill PDF forms with X/FDF data and/or flatten forms, generate FDF data stencils from PDF forms, apply a background watermark or a foreground stamp, report PDF metrics, bookmarks, and metadata, add/update PDF bookmarks or metadata, attach files to PDF pages or the PDF document, unpack PDF attachments, burst a PDF document into single pages, uncompress and re-compress page streams, and repair corrupted PDF files (where possible).