FAQ:Applications 09

Why do I get "noSuchName" when asking for "sysUpTime" (or similar)?

Assuming that you do have access to this object, the most likely cause is forgetting the instance subidentifier.

If you try walking the 'system' group (or any other part of the MIB tree), you should notice that all of the results have a number after the object name. This is the "instance subidentifier" of that particular MIB instance.

For values in tables (such as the sysORTable), this acts as an index into the table - a very familiar concept. But all SNMP values will display an instance number, whether or not they are part of a table. For non-table objects ("scalars"), this instance subidentifier will always be '.0', and it must be included when making a GET request.

Compare the following:

  $ snmpget -v1 -c public localhost sysUpTime
  Error in packet
  Reason: (noSuchName) There is no such variable name in this MIB.
  This name doesn't exist: system.sysUpTime
  
  $ snmpget -v1 -c public localhost sysUpTime.0
  system.sysUpTime.0 = Timeticks: (69189271) 8 days, 0:11:32.71
 

This is a little less obscure when using SNMPv2c or v3 requests:

  $ snmpget -v 2c -c public localhost sysUpTime
  system.sysUpTime = No Such Instance currently exists

   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?