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Wireshark is the world's foremost network protocol analyzer. It lets you capture and interactively browse the traffic running on a computer network. It is the de facto (and often de jure) standard across many industries and educational institutions.

tcpdump is a common packet analyzer that runs under the command line. It allows the user to intercept and display TCP/IP and other packets being transmitted or received over a network to which the computer is attached.

Netcat is a featured networking utility which reads and writes data across network connections, using the TCP/IP 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.

SmartSniff is a packet sniffer that capture TCP/IP packets and display them as sequence of conversations between clients and servers. You can view the TCP/IP conversations in Ascii mode (for text-based protocols, like HTTP, SMTP, POP3 and FTP) or as hex dump (for non-text base protocols, like DNS). Application can capture TCP/IP packets on your network without installing a capture driver (works only for Windows 2000/XP or greater).

NetworkMiner is a Network Forensic Analysis Tool (NFAT) for Windows. NetworkMiner can be used as a passive network sniffer/packet capturing tool in order to detect operating systems, sessions, hostnames, open ports etc. without putting any traffic on the network. NetworkMiner can also parse PCAP files for off-line analysis and to regenerate/reassemble transmitted files and certificates from PCAP files.

Ettercap is a suite for man in the middle attacks on LAN. It features sniffing of live connections, content filtering on the fly and many other interesting tricks.It supports active and passive dissection of many protocols (even ciphered ones) and includes many feature for network and host analysis.

Colasoft network packet sniffer or network analyzer software for Windows platform, sniff packets, monitor activities and analyze protocols, best tool for network monitoring and troubleshooting, Free trial available, download now.

LANGuardian is the first and only deep packet inspection (DPI) software to provide SMB network managers with root cause information about network and user activity. LANGuardian gives a deeper level of detail than standard flow tools, and is an affordable alternative to premium appliance based DPI tools.

PsPing is a command-line utility for measuring network performance. In addition to standard ICMP ping functionality, it can report the latency of connecting to TCP ports, the latency of TCP and UDP round-trip communication between systems, and the TCP or UDP bandwidth available to a connection between systems. Besides obtaining min, max, and average values in 0.01ms resolution, you can also use PsPing to generate histograms of the results that are easy to import into spreadsheets.

MicroOLAP TCPDUMP is a clone of tcpdump , the most used network sniffer/analyzer for UNIX, compiled with the original tcpdump code (http://www.tcpdump.org/ ), and MicroOLAP Packet Sniffer SDK.

Pirni Pro is a network security tool designed for iOS, and specifically for iPhone and iPod Touch devices. It is capable of intercepting traffic on a wireless network segment, capturing passwords, and regular expressions entered by the user.The core system of Pirni, written in C, is open-source software, and licensed under the GNU General Public License. Pirni Pro is the succeeding version of Pirni, and is commercial software, available in the Cydia Store, for jailbroken Apple devices.FeaturesPirni Pro supports active dissection of all non-ciphered protocols (given that the user has supplied a regular expression for dissection). The application description contains the following: ARP spoof the entire network or any target Watch a live feed over interesting packets collected Manage regular expressions to filter out data, such as site credentials In addition, the software also offers the following features: Password collectors for: HTTPExternal links Root at Everything official website Cydia Link Extensive Tutorial »

Native Cocoa app for capturing and analyzing packets. Similar to Wireshark, but with a native interface (and less features). If you don't like the X11 GTK Wireshark, this is your app.

AirSnare monitors network traffic for unfriendly MAC addresses and alerts you when a MAC address is found that isn't on the friendly list. AirSnare also monitor DHCP requests from clients.