1, Colasoft Network sniffer - Capsa http://www.colasoft.com/

Colasoft Capsa performs real-time packet capturing, 24/7 network monitoring, advanced protocol analyzing, in-depth packet decoding, and automatic expert diagnosing. It allows you to get a clear view of the complex network, conduct packet level analysis, and troubleshoot network problems.

2, Ethereal - http://www.ethereal.com/

3, EtterCap - http://ettercap.sourceforge.net/

4, Snort - http://www.snort.org/

5, WinDump / TCPDump - http://www.tcpdump.org/wpcap.html/

6, DSniff - http://naughty.monkey.org/~dugsong/dsniff/

Scanning Tools

1, Nmap - http://www.nmap.org/ Nmap is a port scanner. A port scanner scans for open ports, such as 80 (http) or 25 (SMTP)

2, Sam Spade - www.samspade.org/ Sam Spade is a multi network query tool with many extra built in utilities, even a tool for spam. It includes utilities such as ping, whois, traceroute, and finger

3, NetScanTools Pro ($199) - http://www.netscantools.com/nstmain.html NetScanTools Pro Edition is an integrated collection of internet information gathering utilities for Windows Vista/2008/2003/XP/2000. Use it to research IP addresses, hostnames, domain names, email addresses, URLs automatically** or with manual tools.

4, SuperScan - http://www.foundstone.com/ SuperScan has the primary purpose of scanning an IP range. It supports extremely fast Host Discovery lookups as well as TCP and UDP port scans thanks to its multi-threaded and asynchronous techniques.

UserManagement - http://www.tools4ever.com/

Complete user account management featuring advanced user creation, modification, removal, mass creation/removal and delegation of administrative tasks. The UserManagemeNT Suite consists of three modules, Professional, Import and Delegation. These modules can operate independently or seamlessly integrated with each other.

AdminMagic - http://www.tools4ever.com/

Full control: Using AdminMagic, you can take over and control users' desktops from your own workstation. Featuring complete mouse and keyboard emulation, you can execute programs, login/logoff, modify device drivers and reboot all from a central location. You can also take screenshots of remote desktops and store/print them for later use. Remote users will not be interrupted and can continue working as they always do.

Advanced System Optimizer - http://www.systweak.com/

Advanced System Optimizer is a system tweaking suite that includes around 30 tools to improve and tweak your PC's performance. It offers an attractive and easy to use interface that organizes all tasks into categories and provides graphical statistics whenever possible. The tools include junk file cleaner, memory optimizer, system information, system files backup, file encryption, safe uninstaller, duplicate file finder, taskbar manager and much more. Advanced System Optimizer also includes an Internet tracks eraser with cookie manager and secure deletion, and even a desktop sticky notes application. Overall, a great bundle that offers a wide range of system tools with extra benefits that are hardly ever found.