Wireshark Download - best network protocol analyzer.
Wireshark is one of the best network protocol analyzers that lets you see what is happening on your network at a microscopic level. It offers support for hundreds of protocols.
Wireshark can analyze live capture and offline data. The application features include standard three-pane packet browser, captured network data can be browsed via a GUI, or via the TTY-mode TShark utility, access to powerful display filters, reach VoIP analysis, live data can be read from Ethernet, IEEE 802.11, PPP/HDLC, ATM, Bluetooth, USB, Token Ring, Frame Relay, FDDI, and others (depending on your platform).
Wireshark can read and write many different capture file formats including tcpdump (libpcap), Pcap NG, Catapult DCT2000, Cisco Secure IDS iplog, Microsoft Network Monitor, Network General Sniffer (compressed and uncompressed), 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, and many others.
Wireshark can also capture files compressed with gzip can be decompressed on the fly, decrypt many protocols including IPsec, ISAKMP, Kerberos, SNMPv3, SSL/TLS, WEP, and WPA/WPA2, applies color rules can be to the packet list for quick, intuitive analysis and output data can be exported to XML, PostScript, CSV, or plain text.
You can download Wireshark 2.5.0 for Windows Mac, and Linux.