Wireshark
(ver 1.2.18)
Freeware


Wireshark (formerly known as Ethereal) is the world's foremost 
network protocol analyzer. It lets you capture and interactively 
browse the traffic running on a computer network. 


Wireshark has a rich feature set which includes the following:

    * Deep inspection of hundreds of protocols, with more being 
      added all the time
    * Live capture and offline analysis
    * Standard three-pane packet browser
    * Multi-platform: Runs on Windows, Linux, OS X, Solaris, 
      FreeBSD, NetBSD, and many others
    * Captured network data can be browsed via a GUI, or via the 
      TTY-mode TShark utility
    * The most powerful display filters in the industry
    * Rich VoIP analysis
    * Read/write many different capture file formats: 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
    * Capture files compressed with gzip can be decompressed on the fly
    * 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)
    * Decryption support for many protocols, including IPsec, ISAKMP, 
      Kerberos, SNMPv3, SSL/TLS, WEP, and WPA/WPA2
    * Coloring rules can be applied to the packet list for quick, 
      intuitive analysis
    * Output can be exported to XML, PostScript®, CSV, or plain text 


NOTE: This is the last version compatible with Windows 2000 (due to the 
	dependency on WinPcap, which after version 4.1.2 is no longer compatible).