I am running Centos 6.3 and attempting to use snmp v3 to query OID's on this server. Running Paessler's(https://kb.paessler.com) snmp tester 5.1.3 I get a no response from host. I have made sure that my iptables do not have any odd firewall settings. I can verify that snmpd is listening on port 161. I have also made sure that SELinux is fully disabled. I am able to install this on Centos 7.1 without any issue. I have done a tail on the messages in var/log/messages and can see incoming traffic for snmpd i.e emc(https://goo.gl/S92kpR). I am stumped and have no idea why this will work on one version of this OS but not another. I wonder if anyone has any suggestions.