A filter is a piece of software which examines email or internet data and decides whether to send it on, discard it or quarantine it, by following a set of rules.

A filter specifies what packets will be used. It is also used in firewalls to determine which packets get blocked and in sniffers to determine which packets get displayed.

A term used to describe the way a bridge examines a packet and decides on the basis of its address tables whether or not the packet should be forwarded.

An action of the switch to discard certain types of data packets.

This is an operating parameter used in LAN bridges and routers that when set, will cause these devices to block the transfer of packets from one LAN to another.

Process or device that screens packets based on certain characteristics, such as source address, destination address, or protocol, and forwards or discards packets that match the filter. Filters are used to control data packets or local packets. See also packet.