Ike-scan : VPN detector/scanner
Ike-scan exploits transport characteristics in the Internet Key Exchange (IKE) service, the mechanism used by VPNs to establish a connection between a server and a remote client. 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.