Description:

ettercap is a network sniffer/interceptor/logger for ethernet LANs (both
switched or not). It supports active and passive dissection of many protocols
(even ciphered ones, like SSH and HTTPS). Data injection in an established
connection and filtering (substitute or drop a packet) on the fly is also
possible, keeping the connection sincronized. Many sniffing modes were
implemented to give you a powerful and complete sniffing suite. Plugins are
supported. It has the ability to check whether you are in a switched LAN or not,
and to use OS fingerprints (active or passive) to let you know the geometry of
the LAN. The passive scan of the lan retrives infos about: hosts in the lan,
open ports, services version, type of the host (gateway, router or simple host)
and extimated distance in hop.

ettercap-NG with ncurses interface