Hello everyone,

We want to monitor CPU usage on an Alteon Load Balancer appliance. SNMP is the privileged approach, as the network team wants to avoid using the REST API for performance reasons.

They enabled SNMPv3 on the appliance, and I have issues with the usual check_snmp plugin, as it seems to support only “sha” and “aes” as opposed to the required sha-256 and aes-256.

Here is the current output I get:

# /usr/lib64/nagios/plugins/check_snmp -P 3 -U $snmpUser -L authPriv -a SHA-256 -A $snmpAuthPassword -x AES-256 -X $snmpPrivPassword -t 3 -H $snmpTarget -o .1.3.6.1.2.1.1.3.0
External command error: Invalid authentication protocol specified after -a flag: SHA-256
USAGE: snmpget [OPTIONS] AGENT OID [OID]...
  Version:  5.7.2
  Web:      http://www.net-snmp.org/
  Email:    net-snmp-coders@lists.sourceforge.net
OPTIONS:
[...]
 # /usr/lib64/nagios/plugins/check_snmp -P 3 -U $snmpUser -L authPriv -a SHA -A $snmpAuthPassword -x AES -X $snmpPrivPassword -t 3 -H $snmpTarget -o .1.3.6.1.2.1.1.3.0
External command error: snmpget: Authentication failure (incorrect password, community or key)
The credentials are OK, they work if the SNMP agent is configured with just AES and SHA instead of AES-256 and SHA-256.
Could anyone propose a solution to our issue, for instance by recommending an alternative SNMP plugin with AES-256 and SHA-256 support?
Thank you,
PS: Environment is RHEL, same behaviour under 7.9 and 8.9
              
Thanks a lot!
Yes indeed, having the underlying net-snmp package supporting the requested protocols is a prerequisite.
In our case, it was more than that, it had to do with a known bug: check_snmp 2.4.8 shows “No valid data returned” while warnging/crirital range was set · Issue #769 · nagios-plugins/nagios-plugins (github.com)
After upgrading the plugin to 2.4.10 the problem was solved.
Best regards,