What is Stateful Inspection
A type of firewall which relies on tracking the status of a network
connection and a rulebase. The handshake at the start of a network connection is
observed and monitored, and if a successful connection is established, the
firewall then makes an entry in a table to allow all future traffic for that
connection to pass freely. The advantage is that a very high degree of security
can be achieved and virtually all network based attacks can be thwarted with
minimal performance impact.
Many stateful inspection firewalls also provide some application proxy
capabilities for various types of network traffic. This allows them to filter
requests and screen content.
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