In Cain's Password & Sniffer Helpers, a passive sniffer will see which traffic?

• A. Traffic From A Gateway
• B. All Traffic On The LAN
• C. Traffic Only On The WAN
• D. Only Traffic To Or From The Attacker's Own System

Answer: (D)

Passive sniffing means listening without altering or redirecting traffic. On a typical switched Ethernet network, frames are delivered only to their intended recipient, unless the adapter is in promiscuous mode or the switch mirrors ports. Because the sniffer is passive, it doesn’t force traffic to be sent to it or switch traffic from other hosts to it. Therefore, it only sees traffic that is addressed to or originated from the attacker’s own machine. The other options describe scenarios that require seeing traffic beyond what the attacker’s host directly sends or receives (all LAN traffic, WAN traffic, or gateway traffic), which isn’t provided by a simple passive sniffer.