This object specifies whether the SNMP agent enforces
the use of encryption for SNMPv3 messages globally on
all the users in the system.
The 'vacmAccessSecurityLevel' determines the acceptable
security levels per group and is set to noAuthnoPriv
default unless otherwise configured. The actual access
to the mib objects in a SNMP message is controlled by
vacmAccessTable. This object provides the configuration
at a higher level to enforce privacy without any
introspection of the mib objects in the SNMP message.
When the privacy is enforced globally, for any SNMPv3
PDU request with securityLevel of either 'noAuthNoPriv'
and 'authNoPriv', the SNMP agent responds with an
'authorizationError'.