A、Configure SNMP with only read-only community strings.

B、Encrypt TFTP and syslog traffic in an IPSec tunnel.

C、Implement RFC 3704 filtering at the perimeter router when allowing syslog access from devices on the outside of a firewall.

D、Synchronize the NTP master clock with an Internet atomic clock.

E、Use SNMP version 2.

F、Use TFTP version 3 or above because these versions support a cryptographic authentication mechanism between peers.