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.
Nmap ("Network Mapper") is a utility for network exploration, administration, and security auditing. It uses IP packets in novel ways to determine which hosts are available online (host discovery), which TCP/UDP ports are open (port scanning), and what applications and services are listening on each port (version detection). It can also identify remote host OS and device types via TCP/IP fingerprinting. Nmap offers flexible target and port specifications, decoy/stealth scanning for firewall and IDS evasion, and highly optimized timing algorithms for fast scanning.
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.
PeaZip is a cross-platform file archiver utility that provides a unified portable GUI for many open source technologies like 7-Zip, FreeArc, PAQ, UPX, etc. Creates 7Z, ARC, BZ2, GZ, *PAQ, PEA, QUAD/BALZ, TAR, UPX, WIM, XZ, and ZIP files. It extracts more than 150 archive types: ACE, ARJ, CAB, DMG, ISO, LHA, RAR, UDF, ZIPX, and more. Features of PeaZip include extracting, creating, and converting multiple archives at once, creating self-extracting archives, split/join files, strong encryption with two factor authentication, an encrypted password manager, secure deletion, find duplicate files, calculate hashes, and export job definitions as scripts.
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.
Botan is a crypto library written in C++. It provides a variety of cryptographic algorithms, including common ones such as AES, MD5, SHA, HMAC, RSA, Diffie-Hellman, DSA, and ECDSA, as well as many others that are more obscure or specialized. It also offers SSL/TLS (client and server), X.509v3 certificates and CRLs, and PKCS #10 certificate requests. A message processing system that uses a filter/pipeline metaphor allows for many common cryptographic tasks to be completed with just a few lines of code. Assembly and SIMD optimizations for common CPUs offers speedups for critical algorithms like AES and SHA-1.
chntpw is a Linux utility to (re)set the password of any user that has a valid (local) account on your WinNT or Win2000 system, by modifying the crypted password in the registry's SAM file. You do not need to know the old password to set a new one. It works offline (i.e., you have to shutdown your computer and boot off a linux floppy disk). The bootdisk includes stuff to access NTFS partitions and scripts to glue the whole thing together. This utility works with SYSKEY and includes the option to turn it off. A bootdisk image is provided.
DeleGate is a multi-purpose application level gateway or proxy server that mediates communication of various protocols, applying cache and conversion for mediated data, controlling access from clients, and routing toward servers. It translates protocols between clients and servers, converting between IPv4 and IPv6, applying SSL (TLS) to arbitrary protocols, merging several servers into a single server view with aliasing and filtering. It can be used as a simple origin server for some protocols (HTTP, FTP, and NNTP).
FreeRADIUS is a high-performance, highly configurable, and feature-rich RADIUS server. Supported features include EAP (wireless authentication, PEAP, TTLS), MySQL, PostgreSQL, Oracle, LDAP, X9.9 token cards, VMPS, and many more. It comes with more than 50 vendor dictionaries, and interoperates with many others. It is the only open source RADIUS server that has implemented EAP, and it is currently deployed in multiple million-user systems.
LinOTP is a solution for strong two-factor authentication with one time passwords. It features a modular architecture into which UserIdResolver, authentication, and OTP calculation modules can be plugged. It includes UserIdResolver modules for LDAP/AD, SQL, and flat file user databases, and authentication modules for PAM and RADIUS. New modules can be developed easily. Supported tokens are HMAC-OTP/HOTP (RFC 4226/ OATH compliant), Aladdin eToken PASS, eToken NG-OTP, Safeword Alpine, Yubikey, Google Authenticator, motp, SMS OTP/Mobile TAN, and a Simple Pass token for users without token hardware. TOTP is supported, along with a new algorithm for daily passwords for applications not supporting RADIUS. CLI, Web, and GTK+ GUI clients are available for management. LinOTP features multi-client capability, redundancy, and a self-service portal. It has been used with PAM for local and SSH logins, Apache, VPN, and Windows Terminal Server, and is OATH certified.