WinPcap, a free Windows port of the UNIX libpcap packet-capture library, is also necessary to run Nmap, WinDump, and Snort on the Windows platform. Nmap is a great free port scanner, and WinDump is the Windows version of tcpdump, a command-line protocol analyzer similar to Tethereal. Snort is a popular open-source Intrusion Detection System (IDS). You can download Nmap from http://www.insecure.org/nmap, WinDump from http://windump.polito.it, and Snort from http://www.snort.org/dl/binaries/win32. Be aware that the current version of WinPcap can't capture 802.11 wireless packets in promiscuous mode; hence, Ethereal can display only the packets going to and from your own wireless adapter card.