Re: Snmpget in net-snmp 5.2.1 hangs on windows 2003

Hi Jim.

Mohr James wrote:
> In order to record performance data, we have a construct that looks like
> this:
> 
> - Nagios starts an NRPE job on another machine which starts a perl
> script on a Windows 2003 machine
> - the perl script uses the snmpget command from net-snmp 5.2.1 to read a
> single value from a remote machine. 
> - The value is set in the perl script simply by $value=`$command`. (I am
> not using the SNMP perl modules)
> -  The OID .1.3.6.1.4.1.1.1.101.1 is defined like this in snmpd.conf: 
> exec .1.3.6.1.4.1.1.1 /usr/bin/perl /opt/elaxy/bin/get_cpu_usage.pl
> - This value is then written to a MS SQL Database using osql. 
> 
> What is happening is that I see dozens of snmpget.exe programms running
> (occassionally a couple of perl.exe processes). Unfortunately, I see no
> way of figuring out to where these processes are connected, so I cannot
> tell if there are specific machine causing the problems. Using netstat,
> I do see a number of connections to the MS SQL database in TIMEWAIT.
> However, since we are checking a couple of dozens machines, this is not
> surprising. 
> 
> The Nagios is reporting both "CHECK_NRPE: Socket timeout after 10
> seconds." and "connection refused". Obviously this could be a purely
> Nagios problem, however, as far as I can see it seems to be behaving
> correctly. Plus, we have the dozens of snmpget processes that do not go
> away. 

Do the snmpget.exe commands eventually disappear?

I suspect the timeouts are because snmpget is taking too long to 
respond, probably because of a bad community string.  The agent won't 
respond with a 'wrong community string'.  The client just keeps trying 
until the timeout occurs.  I'm not sure about the "connection refused" 
errors.

The default timeout for snmpget (and other commands) is 1 second, and 
the default retries is 5 (man snmpcmd).  Try reducing the retries to 2 
using '-r 2'.

Snmpget errors are sent to STDERR.  To include STDERR in the result, use 
$value=`$command 2>&1`;

If you want to handle the errors by exit code, you can capture it from 
the command using:

$value=`$command`;
$errorlevel = $? >> 8;

Alex



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