Nessus is the world's most used system vulnerability scanner and analysis software. It is a free, powerful, frequently updated, and easy-to-use remote system security scanner with powerful features.
Nessus is constantly updated and has over 70,000 plug-ins. The Key features include remote and local (authenticated) security checks, a client/server architecture with a web-based interface, and an embedded scripting language to write your plug-ins or understand existing plug-ins.
Nessus gives you a lot of options when it comes to running actual vulnerability scans. For example, you will be able to scan individual computers, IP address ranges, or complete subnets. In addition, over 107130 vulnerability plugins in Nessus allow you to specify individual vulnerabilities or groups of vulnerabilities to test. Finally, in contrast to other tools, Nessus does not assume that explicit services are running on common ports; instead, it exploits these vulnerabilities.
The basic workflow of the Nessus tool is to log in, create or configure a policy, run a scan and analyze the results. Configuring a policy is a vulnerability test that you can perform on the target machine. First, click the Policy tab on the left side of the screen under Resources. Next, click the New Policy button to create a new policy. Then, under the Scanner tab, select a policy template based on the scan requirements, such as Basic Scan, Host Discovery, Web Application Testing, etc. Based on this type, Nessus will prompt you to select a different option.