[mrtg] Re: SNMP get problem.

Jan Hugo Prins jhp at jhprins.org
Tue Aug 30 16:19:39 MEST 2005

> Jan Hugo,
> Sorry,  missed the first message.
> About your configfile:
> In the options line you use 'Gauge' and "Absolute'. A counter can never
> belong to two different types at the same moment.
> An other point in your configfile:
> I doubt the oid you are monitoring is a 64bit counter. Temperature is
> usually given in 32bit counters.
> About the error:
> If you run MRTG in debug mode it will also give informational messages.
> Basic logging is usually sufficient to tell you what is wrong.
> The first error you get is the following:
> ---------------------------
> SNMP Error:
> no response received
> SNMPv2c_Session (remote host: "" [].161)
>                    community: "READSTRING"
>                   request ID: 255616923
>                  PDU bufsize: 8000 bytes
>                      timeout: 2s
>                      retries: 5
>                      backoff: 1)
> ---------------------------
> This tells you the SNMP communication from your MRTG host to the target
> and back is somehow broken.
> There can be several reasons for this. To name a few common ones:
> SNMP is not running on the target host.
> Community string in your MRTG config file doesn't match the one on the
> target host.
> SNMP traffic between the MRTG host and the target is blocked in your
> network.
> ...
> Before digging into MRTG the SNMP communication has to be running. To
> solve problems with SNMP you can use a mibbrowser. Since you are using
> Windows I recommend Getif (http://www.wtcs.org/snmp4tpc/getif.htm)
> Hth,
> Jan.

What I also mentioned in my first message is that snmpwalk from the
specified system is working perfectly and all the values are properly
returned. It only fails when tried from within mrtg.

For you some snmpwalk info:
C:\Program Files\mrtg\bin>snmpwalk -v 2c -c READSTRING
SNMPv2-SMI::enterprises.17587. = INTEGER: 44
SNMPv2-SMI::enterprises.17587. = INTEGER: 41

C:\Program Files\mrtg\bin>snmpwalk -v 2c -c READSTRING
SNMPv2-SMI::enterprises.17587. = INTEGER: 32
SNMPv2-SMI::enterprises.17587. = INTEGER: 48

As you can see the value that is returned is indeed a normal 32 bit value.
Don't know where I mentioned that I needed to get a 64 bit value back.

When I look further down in the debug output I see the following line:
WARNING: no data for at
Skipping further queries for Host in this round.

For me this looks like he is trying to request OID instead of and
this OID is not available. When I try to request this OID with snmpwalk I
receive the 2 underlying OID's but mrtg doesn't get them. Maybe MRTG tries
to request the OID's more specificly? snmpget also returns an error
telling me that the OID is not available.

C:\Program Files\mrtg\bin>snmpget -v 2c -c READSTRING
Error in packet
Reason: (noSuchName) There is no such variable name in this MIB.
Failed object: SNMPv2-SMI::enterprises.17587.

Removed the Absolute parameter, but this does not change my problem.

Jan Hugo Prins

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