Network administrators have just configured SSH on their target router and have now discovered that an intruder has been using this router to perform a variety of malicious attacks. What have they most likely forgotten to do and which Cisco IOS commands do they need to use to fix this problem on their target router?
A.
forgot to reset the encryption keys using the crypto key zeroize rsa Cisco IOS global configuration
command
B.
forgot to close port 23 and they need to issue the no transport input telnet Cisco IOS global configuration command
C.
forgot to disable vty inbound Telnet sessions and they need to issue the line vty 0 4 and the no transport input telnet Cisco IOS line configuration commands
D.
forgot to restrict access to the Telnet service on port 23 using ACLs and they need to issue the access-list 90 deny any log Cisco IOS global configuration command, and the line vty 0 4 and access-class 90 in Cisco IOS line configuration commands