If footprinting is the equivalent of casing a place for information, then scanning is equivalent to inspecting the walls for doors and windows as potential entry points. During footprinting, we obtained a list of IP network blocks and IP addresses through a wide variety of techniques including WHOIS and ARIN queries. These techniques provide the security administrator (and hacker) with valuable information about the target network, including employee names and phone numbers, IP address ranges, DNS servers, and mail servers. In this chapter, we will determine what systems are listening for inbound network traffic (aka “alive”) and are reachable using a variety of tools and techniques. We will also look at how you can bypass firewalls ...

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