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ike-scan is a command-line tool that uses the IKE protocol to discover, fingerprint and test IPsec VPN servers. It scans IP addresses for VPN servers by sending a specially crafted IKE packet to each host within a network. Most hosts running IKE will respond, identifying their presence. The tool then remains silent and monitors retransmission packets. These retransmission responses are recorded, displayed and matched against a known set of VPN product fingerprints. ike-scan can VPNs from manufacturers including Checkpoint, Cisco, Microsoft, Nortel, and Watchguard.
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Latest release: version 1.9 on Jan. 24, 2007 (13 years ago).
Amap is a great tool for determining what application is listening on a given port. Their database isn't as large as what Nmap uses for its version detection feature, but it is definitely worth trying for a 2nd opinion or if Nmap fails to detect a service. Amap even knows how to parse Nmap output files. This is yet another valuable tool from the great guys at THC.
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Latest release: version 5.4 on April 1, 2011 (8 years, 10 months ago).
NBTScan is a program for scanning IP networks for NetBIOS name information (similar to what the Windows nbtstat tool provides against single hosts). It sends a NetBIOS status query to each address in a supplied range and lists received information in human readable form. For each responded host it lists IP address, NetBIOS computer name, logged-in user name and MAC address. The original nbtscan was written by Alla Bezroutchko. Steve Friedl has written an alternate implementation.
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Latest release: version 1.5.1 on June 1, 2003 (16 years, 8 months ago).