Which tool is an attacker most likely to use to attempt to view packets containing data in clear text?

WireShark is a network protocol analyzer that allows users to capture and interactively browse the traffic on a computer network. It provides the capability to view packets in real-time and can decode various protocols to present data in a readable format. When an attacker uses WireShark, they are able to see packet contents, including those that are transmitted in clear text, meaning that no encryption is applied.

WireShark's functionality allows attackers to inspect all types of network traffic, making it a powerful tool for information gathering and analysis of communication across networks. This is particularly useful in scenarios where sensitive data such as usernames, passwords, or other confidential information might be sent without encryption.

In contrast, SSLstrip is a tool designed to perform man-in-the-middle attacks on HTTPS traffic, and while it can potentially intercept data, it specifically targets encrypted communications rather than general packet analysis. Nessus is primarily a vulnerability scanner that assesses systems for weaknesses, and it does not focus on packet capture or analysis. Netcat is a versatile networking utility that can be used for various purposes, including creating connections and data transfer, but it is not specifically designed for viewing packets in clear text like WireShark is.