DFF (Digital Forensics Framework) is a simple but powerful tool with a flexible module system which will help you in your digital forensics works, including file recovery due to error or crash, evidence research and analysis, etc. DFF provides a robust architecture and some handy modules.
PTK is an alternative advanced interface for the TSK (The Sleuth Kit) suite. It was developed from scratch. Besides providing the functions already present in Autopsy, it implements numerous new features essential during forensic activity. PTK provides a graphical and highly professional interface based on AJAX technology. It also offers a great deal of features like analysis, search, and management of complex cases of digital investigation.
The Cryptographic Implementations Analysis Toolkit (CIAT) is a compendium of command line and graphical tools whose aim is to help in the detection and analysis of encrypted byte sequences within files (executable and non-executable). It is particularly helpful in the forensic analysis and reverse engineering of malware using cryptographic code and encrypted payloads.
Yet Another Flowmeter (YAF) is a tool for network flow capture, primarily designed to operate efficiently on white box hardware and generate IPFIX flow records. It is designed to operate primarily on Unix-based systems (including Mac OS X), and is supported by the Network Situational Awareness team at CERT.
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).
Lynis is an auditing and hardening tool for Unix derivatives like Linux/BSD/Solaris. It scans systems to detect software and security issues. Besides security-related information, it will also scan for general system information, installed packages, and possible configuration mistakes. The software is aimed at assisting automated auditing, software patch management, and vulnerability and malware scanning of Unix-based systems.