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Security+ Training Guide by Todd King

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Infrastructure Security

  • A firewall is a hardware or software system designed to protect one network from another network. The various types of firewalls are covered in Table 4.

    Table 4. Review of Firewall Types
    Firewall TypeDescription
    Packet filteringUses lists to check the source/destination network address, source/destination port, and protocol.
    Circuit-level gatewayMonitors at the Session layer of the OSI and checks relationships between hosts to ensure it is allowed traffic.
    Application-level gatewayKnown as a proxy, this device functions at the Application layer of the OSI. It has the most complex set of rules and can control access by user ID and policies.
    Stateful inspectionCombination of all three of the other firewall types.
  • A router is an ...

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