Nikto(one of the best web server scanners) http://www.cirt.net/nikto/nikto-1.36.tar.bz2 NMAP (excellent security tool - port scanner, OS detector e.t.c.) Here's its download page: http://ftp.iasi.roedu.net/mirrors/download.insecure.org/nmap/nmap_download.html NetCat Another security tool - port scanning, port listening e.t.c. It's even called TCP/IP Swiss Army Knife. Windows version: http://www.vulnwatch.org/netcat/nc111nt.zip Linux version: http://www.vulnwatch.org/netcat/nc110.tgz Wireshark - the best port sniffer Windows version: http://wireshark.dsmirror.nl/download/win32/wireshark-setup-0.99.6a.exe Linux source-code: http://www.wireshark.org/download/src/wireshark-0.99.6.tar.gz