A network sniffer is a software program or a hardware device that is capable of monitoring the network data. It is usually used to examine the network traffic by copying the data without altering the content. With a network sniffer, you can see what information is available in your network.

Previously, network sniffers were used by network engineers to help them solve network problems, but it can also be used for malicious purposes. If your network data is not encrypted and your network uses a hub to connect all the computers, it is very easy to capture your network traffic, such as your username, password, and e-mail content. Fortunately, things become a little bit complex if your network is using a switch, but your data can still be captured.

There are many tools that can be used as network sniffers. In this section, we will describe some of those which are included in Kali Linux. You may want to do network spoofing (refer to the Network spoofing tools section) first because...