The Analysis Console for Intrusion Databases (ACID) is a PHP-based analysis engine to search and process a database of security events generated by various IDSes, firewalls, and network monitoring tools. ACID has the ability to analyze a wide variety of events which are post-processed into its database.

AIDE (Advanced Intrusion Detection Environment) is a free replacement for Tripwire. It does the same things as the semi-free Tripwire and more. It creates a database from the regular expression rules that it finds from the config file. Once this database is initialized it can be used to verify the integrity of the files. It has several message digest algorithms (md5,sha1,rmd160,tiger,haval,etc.) that are used to check the integrity of the file. More algorithms can be added with relative ease. All of the usual file attributes can also be checked for inconsistencies. It can read databases from older or newer versions.

AirSnort is a wireless LAN (WLAN) tool that recovers encryption keys. It was developed by the Shmoo Group and operates by passively monitoring transmissions, computing the encryption key when enough packets have been gathered.

A GTK+ based network "swiss-army-knife" Cheops gives a simple interface to most network utilities, maps local or remote networks and can show OS types of the machines on the network.

chkrootkit is a tool to locally check for signs of a rootkit.

his popular and well-engineered suite by Dug Song includes many tools. dsniff, filesnarf, mailsnarf, msgsnarf, urlsnarf, and webspy passively monitor a network for interesting data (passwords, e-mail, files, etc.). arpspoof, dnsspoof, and macof facilitate the interception of network traffic normally unavailable to an attacker (e.g, due to layer-2 switching). sshmitm and webmitm implement active monkey-in-the-middle attacks against redirected SSH and HTTPS sessions by exploiting weak bindings in ad-hoc PKI.

Ethereal is a free network protocol analyzer for Unix and Windows. It allows you to examine data from a live network or from a capture file on disk. You can interactively browse the capture data, viewing summary and detail information for each packet. Ethereal has several powerful features, including a rich display filter language and the ability to view the reconstructed stream of a TCP session. A text-based version called tethereal is included.

Ettercap is a terminal-based network sniffer/interceptor/logger for ethernet LANs. It supports active and passive dissection of many protocols (even ciphered ones, like SSH and HTTPS). Data injection in an established connection and filtering on the fly is also possible, keeping the connection synchronized. Many sniffing modes were implemented to give you a powerful and complete sniffing suite. Plugins are supported. It has the ability to check whether you are in a switched LAN or not, and to use OS fingerprints (active or passive) to let you know the geometry of the LAN.

fping is a ping(1) like program which uses the Internet Control Message Protocol (ICMP) echo request to determine if a host is up. fping is different from ping in that you can specify any number of hosts on the command line, or specify a file containing the lists of hosts to ping. Instead of trying one host until it timeouts or replies, fping will send out a ping packet and move on to the next host in a round-robin fashion. If a host replies, it is noted and removed from the list of hosts to check. If a host does not respond within a certain time limit and/or retry limit it will be considered unreachable.

Helix is a customized distribution of the Knoppix Live Linux CD. Boot the CD and you have Helix. That includes customized linux kernels (2.4.27 & 2.6.7), Fluxbox window manager, Excellent hardware detection and many applications. Helix has been modified to specifically not touch the host computer and be forensically sound. Helix also has a special Windows autorun side for Incident Response.
Helix focuses on Incident Response & Forensics tools. It is meant to be used by individuals who have a sound understanding of Incident Response and Forensic techniques.

HPing2 is a network tool able to send custom ICMP/UDP/TCP packets and to display target replies like ping does with ICMP replies. It handles fragmentation and arbitrary packet body and size, and can be used to transfer files under supported protocols. Using hping2, you can: test firewall rules, perform [spoofed] port scanning, test net performance using different protocols, packet size, TOS (type of service), and fragmentation, do path MTU discovery, tranfer files (even between really Fascist firewall rules), perform traceroute-like actions under different protocols, fingerprint remote OSs, audit a TCP/IP stack, etc. hping2 is a good tool for learning TCP/IP.

John the Ripper is a fast password cracker, currently available for many flavors of Unix (11 are officially supported, not counting different architectures), DOS, Win32, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. It supports several crypt(3) password hash types which are most commonly found on various Unix flavors, as well as Kerberos AFS and Windows NT/2000/XP LM hashes. Several other hash types are added with contributed patches.

Kismet is an 802.11 layer2 wireless network detector, sniffer, and intrusion detection system. Kismet will work with any wireless card which supports raw monitoring (rfmon) mode, and can sniff 802.11b, 802.11a, and 802.11g traffic.

Kismet identifies networks by passively collecting packets and detecting standard named networks, detecting (and given time, decloaking) hidden networks, and infering the presence of nonbeaconing networks via data traffic.

Knoppix-STD is a bootable CD packed with the Linux OS, Fluxbox Windows Manager, with an emphasis on information security tools.

This is the Metasploit Project. The goal is to provide useful information to people who perform penetration testing, IDS signature development, and exploit research. This site was created to fill the gaps in the information publicly available on various exploitation techniques and to create a useful resource for exploit developers.

Nessus is a remote security scanner for Linux, BSD, Solaris, and other Unices. It is plug-in-based, has a GTK interface, and performs over 1200 remote security checks. It allows for reports to be generated in HTML, XML, LaTeX, and ASCII text, and suggests solutions for security problems.

A simple Unix utility which reads and writes data across network connections, using TCP or UDP protocol. It is designed to be a reliable "back-end" tool that can be used directly or easily driven by other programs and scripts. At the same time, it is a feature-rich network debugging and exploration tool, since it can create almost any kind of connection you would need and has several interesting built-in capabilities.

ngrep strives to provide most of GNU grep's common features, applying them to the network layer. ngrep is a pcap-aware tool that will allow you to specify extended regular or hexadecimal expressions to match against data payloads of packets. It currently recognizes TCP, UDP and ICMP across Ethernet, PPP, SLIP, FDDI, Token Ring and null interfaces, and understands bpf filter logic in the same fashion as more common packet sniffing tools, such as tcpdump and snoop.

ngrep strives to provide most of GNU grep's common features, applying them to the network layer. ngrep is a pcap-aware tool that will allow you to specify extended regular or hexadecimal expressions to match against data payloads of packets. It currently recognizes TCP, UDP and ICMP across Ethernet, PPP, SLIP, FDDI, Token Ring and null interfaces, and understands bpf filter logic in the same fashion as more common packet sniffing tools, such as tcpdump and snoop.

Nmap ("Network Mapper") is a free open source utility for network exploration or security auditing. It was designed to rapidly scan large networks, although it works fine against single hosts. Nmap uses raw IP packets in novel ways to determine what hosts are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running, what type of packet filters/firewalls are in use, and dozens of other characteristics.

Rootkit scanner is scanning tool to ensure you for about 99.9% you're clean of nasty tools. This tool scans for rootkits, backdoors and local exploits.

SARA is a vulnerability assessment tool that was derived from the infamous SATAN scanner. They try to release updates twice a month and try to leverage other software created by the open source community (such as Nmap and Samba).

Scanlogd is a TCP port scan detection tool for linux, originally designed to illustrate various attacks an IDS developer has to deal with, for a Phrack Magazine article. It is designed to be totally safe to use, and will recognize all of the latest nmap scans.

SeekerKit is written to be self-contained. It boots to a fully functional command line workstation all running in RAM disk. All packages contained on this CD have been compiled statically to ensure they run without the need of dynamic libraries.
This program can be downloaded at:
http://www.whitehats.ca/downloads/forensics/SeekerKit.iso

The Sentinel project is designed to be a portable, accurate implementation of all publicly known promiscuous detection techniques. Sentinel currently supports 3 methods of remote promiscuous detection: The DNS test, Etherping test, and ARP test. Support for the ICMP Ping Latency test is under development.
For portability purposes, the Sentinel application uses the libpcap and libnet libraries.

Snort is a lightweight network intrusion detection system, capable of performing real-time traffic analysis and packet logging on IP networks. It can perform protocol analysis, content searching/matching and can be used to detect a variety of attacks and probes, such as buffer overflows, stealth port scans, CGI attacks, SMB probes, OS fingerprinting attempts, and much more. Snort uses a flexible rule based language to describe traffic that it should collect or pass, and a modular detection engine. Many people also suggested that the Analysis Console for Intrusion Databases (ACID) be used with Snort.

Swatch started out as the "simple watchdog" for activly monitoring log files produced by UNIX's syslog facility. It has since been evolving into a utility that can monitor just about any type of log.

Tcpdump is a well-known and well-loved text-based network packet analyzer ("sniffer"). It can be used to print out the headers of packets on a network interface that matches a given expression. You can use this tool to track down network problems or to monitor network activities.

TCT is a collection of programs by Dan Farmer and Wietse Venema for a post-mortem analysis of a UNIX system after break-in. The software was presented first in a Computer Forensics Analysis class in August 1999.

The Sleuth Kit (previously known as TASK) is a collection of UNIX-based command line file system and media management forensic analysis tools. The file system tools allow you to examine file systems of a suspect computer in a non-intrusive fashion. Because the tools do not rely on the operating system to process the file systems, deleted and hidden content is shown.

Tripwire is a file and directory integrity checker. Tripwire is a tool that aids system administrators and users in monitoring a designated set of files for any changes. Used with system files on a regular (e.g., daily) basis, Tripwire can notify system administrators of corrupted or tampered files, so damage control measures can be taken in a timely manner.