An entity is conducting a vulnerability assessment to address potential risks. Ethan, a penetration tester, conducted a scan of the entity by creating a list of the protocols present on the entity's machines to identify the ports associated with services like an email server, a web server, or a database server. Once the services were identified, he assessed the vulnerabilities on each machine and proceeded to perform only the pertinent tests. What is the type of vulnerability assessment solution that Ethan utilized in the given scenario?