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Firewall

A hardware device or software program that monitors and filters incoming and outgoing network traffic depending on rules.

Features

  • traffic type detection
  • source & destination address-port logging
  • usage of an ACL
  • packet filtering (based on destination or type of data contained in the packet)
  • transmission protocol filtering (deny or allow TCP/UDP connections) - called circuit-layer gateways
  • pseudoproxy => all outgoing packets allowed by the firewall look like they're from the firewall itself
  • stateful inspection (session layer) => peek into the packet content when session starts, keep relevant information. if it passes firewall settings, let it through for the rest of the session freely, else DIE

#XIV

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