Our puppet-snmpd module support SNMPv3 very well across a wide range of operating systems. Because o that SNMPv3 is what we use across the board in multiple environments. However, in the rare cases when I have to debug SNMP problems I can never remember the exact snmpwalk command-lines to use. So, here is the usual way to run snmpwalk to figure out if SNMP is providing data:
$ snmpwalk -Os -v 3 -u monitor -l authPriv -a sha -A <auth-pass> -x AES -X <encryption-pass> <hostname>Run from the monitoring server (e.g. LibreNMS configured with puppet-librenms) to make sure basic connectivity and access controls are correct as well. Or against localhost if you're interested in the data and not connectivity.
You may want to install snmp-mibs-downloader or equivalent package as well: it translates numeric OIDs to human-readable names when running snmpwalk.
Hopefully I or somebody else will now find this info when it is needed.
