A network security engineer notices unusual traffic on the network from a single IP attempting to access systems on port 23. Port 23 is not used anywhere on the network. Which of the following should the engineer do to harden the network from this type of intrusion in the future?
A. Disable unnecessary services on servers
B. Disable unused accounts on servers and network devices
C. Implement password requirements on servers and network devices
D. Enable auditing on event logs