| #1 |  Wireshark [1] : Sniffing the glue that holds the Internet together Wireshark (known as Ethereal [2] until a trademark dispute in Summer 2006)     |
| #2 |  Kismet [3] : A powerful wireless sniffer Kismet is an console (ncurses) based 802.11 layer2 wireless network detector, sniffer, and intrusion detection system. |
| #3 |  Tcpdump [4] : 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. |
| #4 |  Cain and Abel [5] : 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. |
| #5 |  Ettercap [6] : In case you still thought switched LANs provide much extra security Ettercap is a terminal-based network sniffer/interceptor/logger for ethernet LANs. |
| #6 |  Dsniff [7] : 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 |
| #7 |  NetStumbler [8] : Free Windows 802.11 Sniffer Netstumbler is the best known Windows tool for finding open wireless access points ("wardriving"). |
| #8 |  Ntop [9] : A network traffic usage monitor Ntop shows network usage in a way similar to what top does for processes. |
| #9 | Ngrep : Convenient packet matching & display ngrep strives to provide most of GNU grep's common features, applying them to the network layer. |
| #10 |  EtherApe [10] : EtherApe is a graphical network monitor for Unix modeled after etherman Featuring link layer, IP and TCP modes, EtherApe displays network activity graphically with a color coded protocols display. |
| #11 |  KisMAC [11] : A A GUI passive wireless stumbler for Mac OS X This popular stumbler for Mac OS X offers many of the features of its namesake |
Links:
[1] http://www.wireshark.org/
[2] http://www.ethereal.com/
[3] http://www.kismetwireless.net/
[4] http://www.tcpdump.org/
[5] http://www.oxid.it/cain.html
[6] http://ettercap.sourceforge.net/
[7] http://www.monkey.org/~dugsong/dsniff/
[8] http://www.stumbler.net/
[9] http://www.ntop.org/
[10] http://etherape.sourceforge.net/
[11] http://kismac.de/