How do I troubleshoot: SNMP OID problem?

[cconstantine]

I have a host where the SNMP "box" under the Availability column is red. The associated error is "Error building ASN.1 representation (Can't build OID for variable)."

I've seen a few other no-responses threads with this problem, so I'm looking for a way to dig into this to figure out the underlying problem(s).

How do I troubleshoot what is wrong, or missing?

Is there an error log somewhere?
...or a way to enable error logging of SNMP work?
Can I figure out if I'm missing a MIB?
...or MIBs are installed in the wrong place?
...Zabbix server configured without SNMP support?
etc...

version info

Zabbix 2.0.9
Ubuntu 12.04LTS
PHP 5.3.10
PHP's NET-SNMP version is 5.4.3

[aib]

Hi, cconstantine!

Did you try to use command

grep SNMP /var/log/zabbix/zabbix_server.log | more

If you need some DEBUG information, you can set DebugLevel to highest level 4 (temporarily, because it generate a lot of lines in your zabbix_server.log file)

# vi /etc/init.d/zabbix_server.conf
......
DebugLevel=4
......

After changing DebugLevel, restart Zabbix server and try to catch SNMP information about your host

tail -f /var/log/zabbix/zabbix_server.log | grep SNMP | grep {your_host_name}

When you fix the problem don't forget to switch DebugLevel back to 3 (or 0) to save your log file from infinite growth.

[cconstantine]

thanks!

Thanks for the helpful directions into debug logging!

I changed the debug level and restarted. Still didn't see any SNMP related errors... lots of debug logging though.

And then I realized the SNMP "block" was now enabled/green. I recently installed some snmp packages on the system, and I must have failed to restart the Zabbix server.

[aib]

I glad to hear that your problem fixed!

[lpic.lt]

Hi ALL!

I have the same problem.

I have loaded new MIB's to a dir, and now snmpget gets the value, but zabbix still receives errors:

snmp_build: unknown failure 24203:20150409:123701.339 SNMP item [memActiveReal] on host [HostName2] failed: first network error, wait for 60 seconds
snmp_build: unknown failuresnmp_build: unknown failure 24197:20150409:123732.661 SNMP item [fwInstallTime] on host [HostName1] failed: first network error, wait for 60 seconds
snmp_build: unknown failure 24323:20150409:123801.081 resuming SNMP checks on host [HostName2]: connection restored
snmp_build: unknown failure 24193:20150409:123802.392 SNMP item [tunnelState[vpn_point_Name]] on host [HostName2] failed: first network error, wait for 60 seconds
snmp_build: unknown failure 24322:20150409:123832.089 resuming SNMP checks on host [HostName1]: connection restored
snmp_build: unknown failure 24317:20150409:123902.093 resuming SNMP checks on host [HostName2]: connection restored
snmp_build: unknown failure 24194:20150409:123903.339 SNMP item [memTotalReal] on host [HostName2] failed: first network error, wait for 60 seconds
[B]snmp_build: unknown failuresnmp_build: unknown failure[/B] 24225:20150409:123934.236 SNMP item [fwNumConn] on host [HostName1] failed: first network error, wait for 60 seconds
snmp_build: unknown failure 24327:20150409:124003.106 resuming SNMP checks on host [HostName2]: connection restored
snmp_build: unknown failure 24259:20150409:124005.224 SNMP item [tunnelState[vpn_Names]] on host [HostName2] failed: first network error, wait for 60 seconds
[B]snmp_build: unknown failuresnmp_build: unknown failure[/B] 24324:20150409:124034.115 SNMP item [haProblemStatus[Filter]] on host [HostName1] failed: another network error, wait for 60 seconds
snmp_build: unknown failure 24318:20150409:124105.117 resuming SNMP checks on host [HostName2]: connection restored
snmp_build: unknown failure 24323:20150409:124134.128 resuming SNMP checks on host [HostName1]: connection restored
snmp_build: unknown failure 24213:20150409:124137.687 SNMP item [haProblemStatus[cphad]] on host [HostName2] failed: first network error, wait for 60 seconds
snmp_build: unknown failuresnmp_build: unknown failure 24257:20150409:124153.582 SNMP item [tunnelState[vpn_point_Newy]] on host [HostName1] failed: first network error, wait for 60 seconds
snmp_build: unknown failure 24321:20150409:124237.140 resuming SNMP checks on host [HostName2]: connection restored
snmp_build: unknown failure 24323:20150409:124253.143 resuming SNMP checks on host [HostName1]: connection restored

mean while, SNMPwalk goes through it... BUT, it hangs for a while and drops me timeout:

.1.3.6.1.4.1.2620.1.1.27.1.11.16.0 = ""
Timeout: No Response from HOST_IP

When I o snmpwalk over "system info" or some specific section, it returns without any error... Also, when I do SNMPGET with exact MIB value (text or number) it is ok, but if snmpwalk, so itreturns me value + error:

Error: OID not increasing...

I think it is good... so problem, is that it gets timeout... is it on OS level or somewhere on zabbix server conf file?

[lpic.lt]

Hi ALL!

I have some interesting findings...

tcpdump do NOT see any requests to that host... But LOG says SNMP requests were sent...

iptables -L -n show, that NO rules are set and ALL chains are with policy ACCEPT...

[lpic.lt]

One more interesting thing, when I have changed MIB to OID, I have received SNMP reply... So one more time, do I need to restart zabbix after a MIB file addition? Or I can do it without restart?

[aquarios]

You can force the "-Cc" option of the SNMPwalk to be applied globally (for all user) - including Zabbix the following way:

printf "dontCheckOrdering 1\n" | sudo tee /etc/snmp/snmpwalk.conf

Also check the "Max repetition count" setting on the host's interface level to prevent the output from being truncated