- Nessus [Vulnerability Scanner]
Premier UNIX vulnerability assessment tool. Nessus is the best free network vulnerability scanner available, and the best to run on UNIX at any price. It is constantly updated, with more than 11,000 plugins for the free (but registration and EULA-acceptance required) feed. Key features include remote and local (authenticated) security checks, a client/server architecture with a GTK graphical interface, and an embedded scripting language for writing your own plugins or understanding the existing ones. Nessus 3 is now closed source, but is still free-of-cost unless you want the very newest plugins. - Wireshark [Packet Sniffer]
Sniffing the glue that holds the Internet together.Wireshark (known as Ethereal until a trademark dispute in Summer 2006) is a fantastic open source 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, delving down into just the level of packet detail you need. Wireshark has several powerful features, including a rich display filter language and the ability to view the reconstructed stream of a TCP session. It also supports hundreds of protocols and media types. A tcpdump-like console version named tethereal is included. One word of caution is that Ethereal has suffered from dozens of remotely exploitable security holes, so stay up-to-date and be wary of running it on untrusted or hostile networks (such as security conferences). - Snort [Intrusion Detection System]
Everyone's favorite open source IDS.This lightweight network intrusion detection and prevention system excels at traffic analysis and packet logging on IP networks. Through protocol analysis, content searching, and various pre-processors, Snort detects thousands of worms, vulnerability exploit attempts, port scans, and other suspicious behavior. Snort uses a flexible rule-based language to describe traffic that it should collect or pass, and a modular detection engine. Also check out the free Basic Analysis and Security Engine (BASE), a web interface for analyzing Snort alerts.
Open source Snort works fine for many individuals, small businesses, and departments. Parent company SourceFire offers a complimentary product line with more enterprise-level features and real-time rule updates. They offer a free (with registration) 5-day-delayed rules feed, and you can also find many great free rules at Bleeding Edge Snort. - Netcat [Utility]
The network Swiss army knife. This simple utility reads and writes data across TCP or UDP network connections. 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, including port binding to accept incoming connections. The original Netcat was released by Hobbit in 1995, but it hasn't been maintained despite its immense popularity. It can sometimes even be hard to find nc110.tgz. The flexibility and usefulness of this tool have prompted people to write numerous other Netcat implementations - often with modern features not found in the original. One of the most interesting is Socat, which extends Netcat to support many other socket types, SSL encryption, SOCKS proxies, and more. It even made this list on its own merits. There is also Chris Gibson's Ncat, which offers even more features while remaining portable and compact. Other takes on Netcat include OpenBSD's nc, Cryptcat, Netcat6, PNetcat, SBD, and so-called GNU Netcat. - Metasploit Framework [Vulnerability Exploitation Tool]
Hack the PlanetMetasploit took the security world by storm when it was released in 2004. No other new tool even broke into the top 15 of this list, yet Metasploit comes in at #5, ahead of many well-loved tools that have been developed for more than a decade. It is an advanced open-source platform for developing, testing, and using exploit code. The extensible model through which payloads, encoders, no-op generators, and exploits can be integrated has made it possible to use the Metasploit Framework as an outlet for cutting-edge exploitation research. It ships with hundreds of exploits, as you can see in their online exploit building demo. This makes writing your own exploits easier, and it certainly beats scouring the darkest corners of the Internet for illicit shellcode of dubious quality. Similar professional exploitation tools, such as Core Impact and Canvas already existed for wealthy users on all sides of the ethical spectrum. Metasploit simply brought this capability to the masses. - Hping2 [packet crafting tool]
A network probing utility like ping on steroids.This handy little utility assembles and sends custom ICMP, UDP, or TCP packets and then displays any replies. It was inspired by the ping command, but offers far more control over the probes sent. It also has a handy traceroute mode and supports IP fragmentation. This tool is particularly useful when trying to traceroute/ping/probe hosts behind a firewall that blocks attempts using the standard utilities. This often allows you to map out firewall rulesets. It is also great for learning more about TCP/IP and experimenting with IP protocols. - Kismet [Packet Sniffer]
A powerful wireless sniffer.Kismet is an console (ncurses) based 802.11 layer2 wireless network detector, sniffer, and intrusion detection system. It identifies networks by passively sniffing (as opposed to more active tools such as NetStumbler), and can even decloak hidden (non-beaconing) networks if they are in use. It can automatically detect network IP blocks by sniffing TCP, UDP, ARP, and DHCP packets, log traffic in Wireshark/TCPDump compatible format, and even plot detected networks and estimated ranges on downloaded maps. As you might expect, this tool is commonly used for wardriving. Oh, and also warwalking, warflying, and warskating, ... - Tcpdump [Packet Sniffer]
The classic sniffer for network monitoring and data acquisition.Tcpdump is the IP sniffer we all used before Ethereal (Wireshark) came on the scene, and many of us continue to use it frequently. It may not have the bells and whistles (such as a pretty GUI or parsing logic for hundreds of application protocols) that Wireshark has, but it does the job well and with fewer security holes. It also requires fewer system resources. While it doesn't receive new features often, it is actively maintained to fix bugs and portability problems. It is great for tracking down network problems or monitoring activity. There is a separate Windows port named WinDump. TCPDump is the source of the Libpcap/WinPcap packet capture library, which is used by Nmap among many other tools. - Cain and Abel [Packet Sniffer]
The top password recovery tool for Windows.UNIX users often smugly assert that the best free security tools support their platform first, and Windows ports are often an afterthought. They are usually right, but Cain & Abel is a glaring exception. This Windows-only password recovery tool handles an enormous variety of tasks. It can recover passwords by sniffing the network, cracking encrypted passwords using Dictionary, Brute-Force and Cryptanalysis attacks, recording VoIP conversations, decoding scrambled passwords, revealing password boxes, uncovering cached passwords and analyzing routing protocols. It is also well documented. - Ettercap [Packet Sniffer]
In case you still thought switched LANs provide much extra securityEttercap 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. - OpenSSH / PuTTY / SSH [Secure Shell]
A secure way to access remote computers.SSH (Secure Shell) is the now ubiquitous program for logging into or executing commands on a remote machine. It provides secure encrypted communications between two untrusted hosts over an insecure network, replacingthe hideously insecure telnet/rlogin/rsh alternatives. Most UNIX users run the open source OpenSSH server and client. Windows users often prefer the free PuTTY client, which is also available for many mobile devices. Other Windows users prefer the nice terminal-based port of OpenSSH that comes with Cygwin. Dozens of other free and proprietary clients exist. You can explore them here or here. - Paros proxy [Web Vulnerability Scanner]
A web application vulnerability assessment proxy.A Java based web proxy for assessing web application vulnerability. It supports editing/viewing HTTP/HTTPS messages on-the-fly to change items such as cookies and form fields. It includes a web traffic recorder, web spider, hash calculator, and a scanner for testing common web application attacks such as SQL injection and cross-site scripting. - Dsniff [Packet Sniffer]
A suite of powerful network auditing and penetration-testing tools.This 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. A separately maintained partial Windows port is available here. Overall, this is a great toolset. It handles pretty much all of your password sniffing needs. - NetStumbler [Packet Sniffer]
Free Windows 802.11 Sniffer. Netstumbler is the best known Windows tool for finding open wireless access points ("wardriving"). They also distribute a WinCE version for PDAs and such named Ministumbler. The tool is currently free but Windows-only and no source code is provided. It uses a more active approach to finding WAPs than passive sniffers such as Kismet or KisMAC. - Netfilter [Firewall]
The current Linux kernel packet filter/firewall. Netfilter is a powerful packet filter implemented in the standard Linux kernel. The userspace iptables tool is used for configuration. It now supports packet filtering (stateless or stateful), all kinds of network address and port translation (NAT/NAPT), and multiple API layers for 3rd party extensions. It includes many different modules for handling unruly protocolssuch as FTP. For other UNIX platforms, see Openbsd PF (OpenBSD specific), or IP Filter. Many personal firewalls are available for Windows (Tiny,Zone Alarm, Norton, Kerio, ...), though none made this list. Microsoft included a very basic firewall in Windows XP SP2, and will nag you incessantly until you install it. - Sysinternals [Utilities, Rootkit Detector]
An extensive collection of powerful windows utilities. Sysinternals provides many small windows utilities that are quite useful for low-level windows hacking. Some are free of cost and/or include source code, while others are proprietary. Survey respondents were most enamored with:
ProcessExplorer for keeping an eye on the files and directories open by any process (like LSoF on UNIX).
PsTools for managing (executing, suspending, killing, detailing) local and remote processes. Autoruns for discovering what executables are set to run during system boot up or login. RootkitRevealer for detecting registry and file system API discrepancies that may indicate the presence of a user-mode or kernel-mode rootkit.
TCPView, for viewing TCP and UDP traffic endpoints used by each process (like Netstat on UNIX). Update: Microsoft acquired Sysinternals in July 2006, promising that “Customers will be able to continue building on Sysinternals' advanced utilities, technical information and source code”. Less than four months later, Microsoft removed most of that source code. Future product direction is uncertain. - Retina [Vulnerability Scanner]
Commercial vulnerability assessment scanner by eEye. Like Nessus, Retina's function is to scan all the hosts on a network and report on any vulnerabilities found. It was written by eEye, who are well known for their security research. - Tripwire [Rootkit Detector]
The grand-daddy of file integrity checkers. 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. An open source Linux version is freely available at Tripwire.Org. UNIX users may also want to consider AIDE, which has been designed to be a free Tripwire replacement. Or you may wish to investigate Radmind, RKHunter, or chkrootkit. Windows users may like RootkitRevealer from Sysinternals. - RKHunter [Rootkit Detector]
An Unix Rootkit Detector. RKHunter is scanning tool that checks for signs of various pieces of nasty software on your system like rootkits, backdoors and local exploits. It runs many tests, including MD5 hash comparisons, default filenames used by rootkits, wrong file permissions for binaries, and suspicious strings in LKM and KLD modules. - Fragroute/Fragrouter [Intrusion Detection System]
A network intrusion detection evasion toolkitFragrouter is a one-way fragmenting router - IP packets get sent from the attacker to the Fragrouter, which transforms them into a fragmented data stream to forward to the victim. Many network IDS are unable or simply don't bother to reconstruct a coherent view of the network data (via IP fragmentation and TCP stream reassembly), as discussed in this classic paper. Fragrouter helps an attacker launch IP-based attacks while avoiding detection. It is part of the NIDSbench suite of tools by Dug Song. Fragroute is a similar tool which is also by Dug Song.
[Source - sectools.org]
