FAQ:Applications 16

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I get an error when trying to get a string-indexed table value - why?

The Net-SNMP library will normally try to interpret string-based index values, and display them in a meaningful manner:

     $ snmpgetnext .... vacmGroupName
     vacmGroupName.3."dave" = theWorkers

The command-line tools will also accept string-valued indexes within an OID, and convert them into the appropriate numeric form before sending an SNMP request. However the Unix shell will typically swallow the quotes around the string index value, before the SNMP tools can get a chance to interpret them.

The answer is to escape the quotes, to protect them from the shell, and allow them to be passed through to the OID parser:

     snmpget ....   vacmGroupName.3.\"dave\"

or

     snmpget ....  'vacmGroupName.3."dave"'

Another alternative is to avoid trying to specify the index value as a string, and provide the numeric subidentifiers directly:

     snmpget .... vacmGroupName.3.4.100.97.118.101

(where '3' indicates SNMPv3, '4' is the length of the string index, followed by the ASCII values of the individual characters).

The command-line option '-Ob' will display the results of querying a string-indexed table in this format:

     $ snmpgetnext -Ob .... vacmGroupName
     vacmGroupName.3.4.100.97.118.101 = theWorkers
   FAQ:Applications
   
  1. How do I add a MIB?
  2. How do I add a MIB to the tools?
  3. Why can't I see anything from the agent?
  4. Why doesn't the agent respond?
  5. I can see the system group, but nothing else. Why?
  6. Why can't I see values in the <ENTERPRISE> tree?
  7. The agent worked for a while, then stopped responding. Why?
  8. Requesting an object fails with "Unknown Object Identifier" Why?
  9. Why do I get "noSuchName" when asking for "sysUpTime" (or similar)?
  10. Why do I sometimes get "End of MIB" when walking a tree, and sometimes not?
  11. How do I use SNMPv3?
  12. Why can't I set any variables in the MIB?
  13. Variables seem to disappear when I try to set them. Why?
  14. Why can't I change sysLocation (or sysContact)?
  15. I get an error when trying to set a negative value - why?
  16. I get an error when trying to query a string-indexed table value - why?
  17. How should I specify string-index table values?
  18. How do I send traps and notifications?
  19. How do I receive traps and notifications?
  20. How do I receive SNNMPv1 traps?
  21. Why don't I receive incoming traps?
  22. My traphandler script doesn't work when run like this - why not?
  23. How can the agent receive traps and notifications?
  24. How big can an SNMP request (or reply) be?
  25. How can I monitor my systems (disk, memory, etc)?
  26. Applications complain about entries in your example 'snmp.conf' file. Why?
  27. OK, what should I put in snmp.conf?
  28. How do I specify IPv6 addresses in tools command line arguments?