While attempting to discover the remote operating system on the target computer, you receive the following results from an nmap scan:
Starting nmap V. 3.10ALPHA9 ( www.insecure.org/nmap/
<http://www.insecure.org/nmap/> )
Interesting ports on 172.121.12.222:
(The 1592 ports scanned but not shown below are in state: filtered)
Port State Service
21/tcp open ftp
25/tcp open smtp
53/tcp closed domain
80/tcp open http
443/tcp open https
Remote operating system guess: Too many signatures match to reliably
guess the OS.
Nmap run completed — 1 IP address (1 host up) scanned in 277.483
seconds
What should be your next step to identify the OS?
A.
Perform a firewalk with that system as the target IP
B.
Perform a tcp traceroute to the system using port 53
C.
Run an nmap scan with the -v-v option to give a better output
D.
Connect to the active services and review the banner information
Explanation:
Most people don’t care about changing the banners presented by applications listening to open ports and therefore you should get fairly accurate information when grabbing banners from open ports with, for example, a telnet application.