Linux Network Information Gathering Lecture (part 2)

This lessons covers port specification and scan techniques and discusses the following examples:
  • -p <port range>: only scan specific ports
  • -F: fast mode. Scan fewer ports than the default scan.
  • -r: scan ports consecutively. Don’t randomize.
  • Top ports <number>: scan <number> most common ports
  • Port ratio <ratio>: scan ports more common than <ratio>
Participants also learn about service/version detection:
  • sV: probe open ports to determine service/version info
  • version intensity <level>: set from 0 (light) to 9 (ty all probes)
  • version light: limit to most likely probes (intensity 2)
  • version all: try every single probe (intensity 9)
  • version trace: showed detailed version scan activity (for debugging)
This lesson also discusses P0f is passive OS fingerprinting and listens to traffic with the intention of identifying operation systems and does not generate its own traffic as well as Tcpdump which prints out a description of the contents of packets on a network to match the Boolean expression.
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