Which type of software is used to monitor usernames and passwords transmitted over a network?

The correct answer for monitoring usernames and passwords transmitted over a network is a sniffer. Sniffer software is designed to capture and analyze the data packets that are transmitted over a network. By intercepting these packets, a sniffer can potentially extract sensitive information, such as usernames and passwords, that are sent in plain text or within non-encrypted communications.

Sniffers are often used in legitimate contexts, such as network troubleshooting, security analysis, and performance monitoring. However, they can also be exploited by cybercriminals to eavesdrop on network traffic and collect sensitive data without the consent of the users involved.

Antivirus software, on the other hand, is intended to detect and remove malware from systems and does not specifically monitor network traffic for captured credentials. Firewalls serve to block unauthorized access to or from a private network, creating barriers to protect data rather than monitoring the data that is being transmitted. Keyloggers, while related to capturing inputs like usernames and passwords, do so by recording keystrokes directly from an individual device rather than monitoring network traffic as a sniffer does.

Understanding the function of different security tools is crucial for network security and identifying potential vulnerabilities within a network environment.