Occurs when one person or program successfully masquerades as another by falsifying data and gains an illegitimate advantage.

The answer is a spoofing attack.

Explanation:

The different protocols related to the TCP/IP suite do not provide the correct ways or mechanisms to authenticate the message's source or destination. Thus, these protocols are vulnerable to spoofing attacks because the applications must take more precautions to know the identity regarding the sending or receiving host.

When there are spoofing attacks in the protocols referring to the TCP/IP suite, there is necessary to use firewalls to solve the problem. We can also see spoofing attacks in e-mails. Spammers use this technique to hide the origin of the respective e-mails and provoke issues like misdirected bounces.  

answer; curiosity;