Wireshark is a powerful tool that has made itself essential for those who study, troubleshoot or dissect network protocols (and packets). To make matters worse, the software is free, open source. and translated into French! Download without hesitation.
Wireshark is a free and open source software project allowing the interception and analysis of packets passing through the user's network. Formerly named Ethereal, it is a more than convincing alternative to the owner Capsa.
Originally developed for Linux (and Solaris) by Gerald Combs in 1998, it has since become cross-platform and also available for Windows and OS X.
Wireshark is mainly used by students for the purpose of understanding protocols or by network professionals, in particular for troubleshooting purposes. Over time, the software has managed to move in the right direction in order to offer a more accessible interface as well as ever more advanced (or even advanced) functionalities.
Wireshark allows in-depth inspection of compressed or uncompressed packets (live and offline) on hundreds of protocols (navigable by the interface or via TTY) and this thanks, in particular, to numerous and powerful filters. Note also that in order to make it easier for the user to read the coloring rules are also applicable to the package lists.
The data can be viewed live from (among others) the Ethernet, IEEE 802.11, PPP / HDLC, ATM, Bluetooth, USB, Token Ring, Frame Relay, FDDI networks.
The software manages capture files in tcpdump (libpcap), Pcap NG, Catapult DCT2000, Cisco Secure IDS iplog, Microsoft Network Monitor, Network General Sniffer, Sniffer Pro, and NetXray, Network Instruments Observer, NetScreen snoop, Novell LANalyzer, RADCOM WAN / LAN Analyzer, Shomiti / Finisar Surveyor, Tektronix K12xx, Visual Networks Visual UpTime, WildPackets EtherPeek / TokenPeek / AiroPeek, etc. Wireshark will allow you to export in XML, PostScript, CSV, or plain text formats.
Finally, note that the sources of help and understanding of the software are extremely numerous online and that many books are being published on the subject.