Exam 200-201 topic 1 question 293 discussion

Answer is A. Filtered state means that the firewall hides the state of the service

Agreed with A, filtered means there's a firewall in the organization

A is correct. Filtered: Nmap cannot determine whether the port is open because packet filtering prevents its probes from reaching the port. The filtering could be from a dedicated firewall device, router rules, or host-based firewall software. https://wiki.onap.org/display/DW/Nmap

Filtered means that a firewall, filter, or other network obstacle is blocking the port so that Nmap cannot tell whether it is open or closed. Closed ports have no application listening on them, though they could open up at any time From OMAP page

This is just another tricky question where both A and C can be valid. I have choosen C because when the port is Filtered, an ICMP unreachable error is sent back. From the result we can see that there is nothing for other ports included in scan (for ex TCP 135) which means that the only reason those appeared with Filtered is because the services are running and a firewall was configured to protect those services. BUT the reason for scan itself is to discover the services running in order to weaponize something against them.

Obviously A.