Many people know that a network is used to transfer information from one point to another. However, many of them don’t know that this very information can be sniffed/eavesdropped. Man-in-the-middle (MITM) is one attack to sniff information sent between end-points. As the name inferred, the attacker wants to be a third person in a supposedly a two-person communication. Let’s make this clear. Suppose Alice and Bob are communicating through a network. Then there is Eve who wants to know what kind of talks that Alice and Bob are in.
Okay, then what? The first thing that Eve has to do is to impersonate both Alice and Bob and put herself “in the middle”. When Alice sends a message to Bob, in reality Alice sends a message to Eve who impersonates Bob. The same thing happens when Bob is sending a message to Alice. Eve receives the message from Bob.
One thing to realize is that both Alice and Bob don’t know that they are being intercepted. This is sweet!