Smarts IP: Invalid length specification or 'Mangled' value error seen in dump of a Smarts IP SM_smnpwalk of a Linux OS running a Net-SNMP SNMP agent

Products

• VMware Smart Assurance

Issue/Introduction

Symptoms:




Invalid length specification or "Mangled" value error seen in dump of a Smarts IP SM_smnpwalk of a Linux OS running a Net-SNMP SNMP agent
Smarts IP SM_smnpwalk (SNMP walk) or discovery of a Red Hat Linux device running NetSNMP terminates after the following error appears in the .walk file or in the log file of the discovery of the device:

.1.3.6.1.2.1.25.3.3.1.1.768".0.0"
.1.3.6.1.2.1.25.3.3.1.1.769".0.0"
SNMP-N-EPARSER-Mangled or incorrect packet; parsing aborted and data
    discarded; in file
    "/work/whitecurrent/FOUNDATION-7.0.2.X-HF/30/smarts/snmp/lib/SNMP_Parser.c
    " at line 1211

Environment

VMware Smart Assurance - SMARTS

Cause

The OID that is at fault here is the hrProcessorLoad (.1.3.6.1.2.1.25.3.3.1.2) OID. This has an expected value of Integer32 (32 bit integer). From a snoop of the underlying packets in the network, it is evident that this OID is returning OID values instead of an integer between 1 and 100 as defined by the MIB. We can see that the values of this OID should be:

Object            hrProcessorLoad

OID               1.3.6.1.2.1.25.3.3.1.2 Type              Integer32 Permission        read-only Status            current Range             0 - 100 MIB               HOST-RESOURCES-MIB ;   -   View Supporting Images

Description       "The average, over the last minute, of the percentage of time that 
                  this processor was not idle. mplementations may approximate this one minute
                  smoothing period if necessary."

In a walk of a sample device, the OID .1.3.6.1.2.1.25.3.3.1.2.768, a sample value returned was as follows in the snoop: "SNMPv2-SMI::mib-2.25.3.1.3

Resolution

This is an SNMP vendor issue as the information returned from the SNMP query is of an incorrect type. This should be addressed by the NetSNMP vendor.

Additional Information

This issue was found in Red Hat Linux running NetSNMP agent 5.1.2 but may affect other versions.