Its been a while since I have posted about some hacking tools and with increasing
 number of emails asking me to do an  article on it, I finally decided to cover it up.Hacking tools
 are developed by some really good coders out there to ease out many complex tasks which 
have to be done manually and took painstakingly great deal of time and effort.All these tools provided here are free of cost,are tried hands on and are being actively developed by community,and if not,their alternatives are provided.To


1. Nmap 
I think everyone has heard of this one, 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.Many systems and network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime. 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 
Nmap(and OS versions) they are running, what type of packet filters/firewalls are in use,and dozens
 of other characteristics. It may be used to discover computers and services on a computer
 network, thus creating a “map” of the network.Nmap runs on most types of computers
 and both console and graphical versions are available. Nmap is free and open source
.Can be used by beginners (-sT) or by pros alike (packet_trace). A very versatile tool, once you
 fully understand the results.
2. Nessus Remote Security Scanner 
Recently went closed source, but is still essentially free. Works with a client-server framework.Nessus is the worlds Nessus Remote Security Scanner most popular vulnerability scanner used in over 75,000 organizations world-wide. Many of the worlds largest organizations are realizing significant cost savings by using Nessus to audit business-critical enterprise devices and applications.
3. Wireshark 
Wireshark is a GTK+-based  Wiresharknetwork protocol analyzer, or sniffer, that lets you capture and interactively browse the contents of network frames. The goal of the project is to create a commercial-quality analyzer for Unix and to give Wireshark features that are missing from closed-source sniffers. Works great on both Linux and Windows (with a GUI), easy to use and can reconstruct TCP/IPStreams! .
4. Cain and Abel 
The swiss knife of hacking tools..Cain & Abel is a password recovery tool for Microsoft Operating Systems. It allows easy recovery of various kind of 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.The program does not exploit any software vulnerabilities or bugs that could not be fixed with little effort.
5. Kismet 
Kismet is an 802.11 layer2 wireless network detector, sniffer, and intrusion detection system. Kismet will work with  Kismetany wireless card which supports raw monitoring (rfmon) mode, and can sniff 802.11b, 802.11a, and 802.11g traffic. A good wireless tool as long as your card supports rfmon
6. NetStumbler
Yes a decent wireless tool for Windows! Sadly not as powerful as it’s Linux counterparts, but it’s easy to use and has a NetStumblernice interface, good for the basics of war-driving. NetStumbler is a tool for Windows that allows you to detect Wireless Local Area Networks (WLANs) using 802.11b, 802.11a and 802.11g. It has many uses:
  1. Verify that your network is set up the way you intended.
  2. Find locations with poor coverage in your WLAN.
  3. Detect other networks that may be causing interference on your network.
  4. Detect unauthorized rogue access points in your workplace.
  5. Help aim directional antennas for long-haul WLAN links.
  6. Use it recreationally for WarDriving.
7. SuperScan
Powerful TCP port scanner, pinger, resolver. SuperScan 4 is an update of the highly popular Windows port scanning tool, SuperScan. If you need an alternative for nmap on Windows with a decent interface, I suggest you check this out, it’s pretty nice.
Alternatively, you can try Angry IP Scanner which is a pretty good replacement for it