Another popular method that can be used to get access to systems is network sniffing. Sniffing is the method of capturing and seeing traffic as it is passed along the network. Many common protocols in use today still send critical and important data over the network without encryption.
Network traffic transmitted without using encryption is usually referred to as plain text because it is human readable and needs no deciphering. Sniffing plain text network traffic is a trivial but powerful means of getting access to systems.
Most network cards work in nonpromiscuous mode, which means that the network card will only transfer the particular traffic that is addressed to it. Promiscuous mode will push the network card to receive all packets that arrive.
To successfully capture (sniff) network traffic that is not usually destined for your computer, you need to make sure your network card is in promiscuous mode. You may be questioning how it is possible that network traffic would reach a machine if the traffic was not addressed to that machine. There are many potential situations where this situation may occur. First, any traffic that is broadcast on the network will be transferred to all connected machines. Another scenario is networks that use hubs rather than switches to route traffic.