network scanner for researchers

 ZMap is a network scanner that enables researchers to
 easily perform Internet-wide network studies. With a single
 machine and a well provisioned network uplink, ZMap is capable of
 performing a complete scan of the IPv4 address space in under 45
 minutes, approaching the theoretical limit of gigabit Ethernet.
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 ZMap can be used to study protocol adoption over time, monitor
 service availability, and help people better understand large systems
 distributed across the Internet.