Attacker must be connected to the network he must also perform arp poisoning to reroute network traffic between victim and for example GW to flow through his machine interface then the ettercap uses taps or hooks into network stack in order to intercept protocol level 3,4,7 packets and modify their content based on precompiled filters/plugiuns.
Yes in so called open system you can sniff packets and use wireshark to dissect them.
It is based on wireshark ability to dissect packet.For example if you want to intercept your neighbour traffic when he watch porno movies (online streaming) i think you need to develop your own wireshark dissector for video compressed content.get nothing relavent. thanx for any help, i have tryd searching google and a number of forums but i cant get an answer anywhere. it seems so simple people dnt evan bother.