FAQ:Applications 09

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

There are a number of possible causes of this (scattered throughout this FAQ, so keep reading!). But one of the most likely snares for the unwary is forgetting the instance subidentifier for 'non-table' objects. If you walk the 'system' tree, you'll notice that all the results (apart from the sysORTable), have a '.0' at the end of the OID. This is the "instance sub-identifier" - which must be included for 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?