firewall(redirected from Packet filter)
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1. A special building material that is placed in walls between buildings or rooms to prevent the spread of fire.
2. A software program designed to prevent unauthorized persons from accessing a computer system.
A set of programs that protects the resources of a private computer network from users of other networks. It screens the messages that attempt to enter or leave the network and permits or denies access to outside users based on pre-programmed rules.