Detecting Software Versions on a Network

A.

The technique the intruder is using to take inventory of the network and obtain information about software versions is banner grabbing.

Banner grabbing is a method used by attackers to collect information about a network and its services. It involves sending requests to network services such as web servers or FTP servers, and examining the banners, or headers, that are returned in the responses. These banners often contain information about the software and version number being used by the service.

Port scanning, on the other hand, is a technique used to identify open ports on a target system. It involves sending packets to a range of port numbers and analyzing the responses to determine which ports are open and potentially vulnerable to attack.

Packet sniffing, also known as network sniffing, is the practice of intercepting and analyzing network traffic in real-time. This can be used to capture sensitive information such as usernames and passwords.

Virus scanning involves using antivirus software to scan for and detect malicious software on a system. This technique is not relevant to the intruder's goal of taking inventory of the network and identifying software versions.

In summary, the intruder in this scenario is using the technique of banner grabbing to obtain information about software versions on the network.