Which three techniques should be used to secure management protocols？（）

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.