Sniffing is a type of security threat that intentionally reads or steal the transmitted data over a network. The tool, used for a sniffing attack, is called the packet sniffer. Sniffing is used by network professional to recognise any network issues. Further, it is also used by intruders to crack encrypted data such as username and password. The intruders can obtain network access if they find out the unencrypted data over the network. For example, the intruder obtains the IP addresses or other sensitive data and find out the vulnerability. After finding the vulnerability of the network, they can attack the network. They also use the protocol analyser to analyse the network.
There are various types of sniffing attacks, such as MAC attack, DHCP attack, DNS poisoning, ARP poisoning attack, etc. In order to protect from sniffing user should encrypt email using Pretty Good Privacy (PGP). In addition, the user can use Secure Shell (SSH) instead of Telnet and Secure File Transfer Protocol (SFTP) instead of File Transfer Protocol (FTP) to protect their data from a sniffing attack.