Create SNMP v3 users without Net-SNMP
Follow these steps to manually (not using net-snmp) create SNMP v3 users in Cent OS:
1. Stop snmp daemon by execute 'service snmpd stop'.
2. Add the following to /var/lib/net-snmp/snmpd.conf
createUser (username) MD5 (password) DES (encryption password)
3. Add the following to /etc/snmp/snmpd.conf
rouser (username) authpriv .1
4. Start the snmp daemon.
Bear in mind that you need to stop snmp before making configuration changes.