A Company Hires a Penetration Tester to Determine If There

A company hires a penetration tester to determine if there are any vulnerabilities in its new VPN concentrator installation with an external IP of 100.170.60.5. Which of the following commands will test if the VPN is available?

A) fpipe.exe -1 8080 -r 80 100.170.60.5
B) ike-scan -A -t 1 --sourceip=spoof_ip 100.170.60.5
C) nmap -sS -A -f 100.170.60.5
D) nc 100.170.60.5 8080 /bin/sh