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Firewall Technologies

The firewall use different methods to examine and control the data traffic passing through in and out of the local network.

Packet Filtering

Packets (small chunks of data) are analysed against a set of filters. Packets that make it through the filters are sent to the requesting system and all others are discarded.

Stateful Inspection

A newer method that doesn't examine the contents of each packet but instead compares certain key parts of the packet to a database of trusted information. Information travelling from inside the firewall to the outside is monitored for specific defining characteristics, and then incoming information is compared to these characteristics. If the comparison yields a reasonable match, the information is allowed through. Otherwise it is discarded.

Proxy

Information from the Internet is retrieved by the firewall and then sent to the requesting system and vice versa.

Related Topics:

Firewall Overview