A hardware device or server software that captures packets transmitted in a network for routine inspection and problem detection. Also called a "sniffer," "packet sniffer," "packet analyzer," "packet sampler," "traffic analyzer" and "protocol analyzer," the hardware analyzer plugs into a port on a network switch and decodes one or more protocols into a human-readable format for the network administrator. It can also store packets for further analysis later on.
In order to alert admins about traffic problems, packets are analyzed in real time. Hardware network analyzers can detect voltage and cable problems, whereas software analyzers cannot. See IPFIX
and port mirroring