Acceso a los datos que circulan por una red de comunicaciones.

The monitoring or recording of data while it is being transmitted over a communications link, without altering or affecting the data. [CNSSI_4009:2010]

Monitoring and recording data that is flowing between two points in a communication system.

http://www.sans.org/security-resources/glossary-of-terms/

(I) An attack that intercepts and accesses information contained in a data flow in a communication system. (See: active wiretapping, end-to-end encryption, passive wiretapping, secondary definition under "interception".) [RFC4949:2007]

(I) A wiretapping attack that attempts only to observe a communication flow and gain knowledge of the data it contains, but does not alter or otherwise affect that flow. (See: wiretapping. Compare: passive attack, active wiretapping.) [RFC4949:2007]