Libmcrypt is a library which provides a uniform interface to several symmetric encryption algorithms. It is intended to have a simple interface to access encryption algorithms in ofb, cbc, cfb, and ecb modes. The algorithms it supports are DES, 3DES, RIJNDAEL, Twofish, IDEA, GOST, CAST-256, ARCFOUR, SERPENT, SAFER+, and more. The algorithms and modes are also modular so you can add and remove them on the fly without recompiling the library.
Sshguard monitors services through their logging activity. It reacts to messages about dangerous activity by blocking the source address with the local firewall. Sshguard employs a clever parser that can transparently recognize several logging formats at once (syslog, syslog-ng, metalog, multilog, raw messages), and detects attacks for many services out of the box, including SSH, several ftpds, and dovecot. It can operate all the major firewalling systems, and features support for IPv6, whitelisting, suspension, and log message authentication.
aircrack-ng is a set of tools for auditing wireless networks. It's an enhanced/reborn version of aircrack. It consists of airodump (an 802.11 packet capture program), aireplay (an 802.11 packet injection program), aircrack (static WEP and WPA-PSK cracking), airdecap (decrypts WEP/WPA capture files), and some tools to handle capture files (merge, convert, etc.).
SILC (Secure Internet Live Conferencing) is a protocol which provides secure conferencing services in the Internet. It can be used to send any kind of messages, in addition to normal text messages. This includes multimedia messages like images, video, and audio stream. All messages in the SILC network are encrypted and authenticated, and messages can also be digitally signed. SILC protocol supports AES, SHA-1, PKCS#1, PKCS#3, X.509, OpenPGP, and is being developed in the IETF. The software is delivered as SILC Client for end users, SILC Server for system administrators, and SILC Toolkit for application developers.
cryptmount is a utility for creating and managing secure filing systems on GNU/Linux systems. After initial setup, it allows any user to mount or unmount filesystems on demand, solely by providing the decryption password, with any system devices needed to access the filing system being configured automatically. A wide variety of encryption schemes (provided by the kernel dm-crypt system and the libgcrypt library) can be used to protect both the filesystem and the access key. The protected filing systems can reside in either ordinary files or disk partitions. The package also supports encrypted swap partitions, and automatic configuration on system boot-up.
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, 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.
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.
AMaViS (A Mail Virus Scanner) scans e-mail attachments for viruses using third-party virus scanners available for UNIX environments. It resides on a UNIX (Linux) machine and looks through the attached files arriving via e-mail, generates reports when a virus is found and sets the delivery on hold.
IPTables-tutorial is a tutorial which explains how to install and set up iptables and netfilters on Linux. It takes you through a usable example file step by step, and helps you understand its basic functionality. The tutorial currently contains 6 different example scripts that may be used freely under GPL licensing terms.