check_snmp can conflict with settings in snmp.conf

[miken32]

In particular, we were trying to use this tool for rate checking; the checks always came back as "UNKNOWN." We enabled verbose mode and went through check_snmp.c until we realized that our system-wide configuration setting of quickPrinting true was messing with the results.

If this tool is expecting a certain output it should be asking for it with the appropriate options (in this case by explicitly passing --quickPrinting=false to snmpget) or – more properly – importing the net-snmp libraries and doing the checks in C instead of running CLI utilities.

[miken32]

Probably also worth mentioning, the output read loop in main() breaks early due to lack of separator character ":" as excpected. But the check at the end for calculate_rate doesn't take the possibility of an early exit from the loop into account. It should also be checking if total_oids > 0. We were seeing verbose outputs like this, but it probably should have been an error condition:

Previous State for 0=`????
/usr/bin/snmpget -Le -t 3 -r 5 -m ALL -v 2c [context] [authpriv] example.com:161 ifInOctets.24
IF-MIB::ifInOctets.24 4103007855
State string=`?b??
SNMP RATE UNKNOWN - | 

[sawolf]

Hi @miken32, thanks for reaching out. Both of your suggestions sound reasonable - We'll be doing another bugfix release sometime this month, and I'll try to at least handle your first suggestion then.