Sniffing works by making use of or altering certain conditions. The goal of sniffing is to observe the traffic that happens to be moving by the system that is performing the sniffing, but under normal conditions of operation any system will only be allowed to see the information addressed directly to it or coming from it. This makes sense, as a system that has to process all the information that flowed by would be bogged down by inefficiency and poor performance - not to mention it would be a security risk as well.
In order to view all of the traffic flowing by, a network adapter needs to switch into what is known as promiscuous mode. To understand promiscuous mode, first understand that under normal conditions a network ...
