Tapping the wire and the air

One of the purest and most raw forms of information capture is to put taps on network and optical fiber cables to snoop on traffic.

 Many commercial vendors provide network taps and SPAN ports on their devices for snooping where they will forward all traffic seen on the particular port to the analyzer system. The technique is shown in the following diagram:

In the case of WLAN or Wi-Fi, the captures can be performed by putting an external wireless receptor into promiscuous mode and recording all the traffic for a particular wireless access point on a particular channel. This technique is shown in the following diagram: