NRPE: No output returned from plugin error

yuris yuris at smtp.com
Thu Jul 1 16:16:57 CEST 2010


I strongly doubt it has any relation to ssl:

NRPE - Nagios Remote Plugin Executor
Copyright (c) 1999-2008 Ethan Galstad (nagios at nagios.org)
Version: 2.12
Last Modified: 03-10-2008
License: GPL v2 with exemptions (-l for more info)
SSL/TLS Available: Anonymous DH Mode, OpenSSL 0.9.6 or higher required
TCP Wrappers Available

this is output from nrpe (Centos binary package) that shows it's 
compiled with ssl/tls support. Openssl library is installed as well.

Anyway. I tried suggested workaround, defining "check_nrpe_no_ssl" as 
"$USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$ -n" and defining service 
as "check_nrpe_no_ssl!check_load" and running nrpe deamon no centos host 
with "-n" option - result is just the same, "NRPE: Unable to read output"

However, when I do "./check_nrpe -H centos.host.com" it does return me 
nrpe version correctly ("NRPE v2.12").

 From all this steps I figured that it is not about ssl at all - nrpe 
version is returned correctly with ssl and without it.

Interesting, that in nagios server debug log I see that remote NRPE 
returns output that nagios check_nrpe cannot parse, it returns similar 
output, that I would get if call /usr/sbin/nrpe without arguments:


[1277983505.131702] [016.2] [pid=17495] Parsing check output...
[1277983505.131711] [016.2] [pid=17495] Short Output: (No output 
returned from plugin)
[1277983505.131719] [016.2] [pid=17495] Long Output:  NRPE Plugin for 
Nagios\nCopyright (c) 1999-2008 Ethan Galstad 
(nagios at nagios.org)\nVersion: 2.12\nLast Modified: 03-10-2008\nLicense: 
GPL v2 with exemptions (-l for more info)\nSSL/TLS Available: Anonymous 
DH Mode, OpenSSL 0.9.6 or higher required\n\nUsage: check_nrpe -H <host> 
[-n] [-u] [-p <port>] [-t <timeout>] [-c <command>] [-a 
<arglist...>]\n\nOptions:\n -n         = Do no use SSL\n -u         = 
Make socket timeouts return an UNKNOWN state instead of CRITICAL\n 
<host>     = The address of the host running the NRPE daemon\n 
[port]     = The port on which the daemon is running (default=5666)\n 
[timeout]  = Number of seconds before connection times out 
(default=10)\n [command]  = The name of the command that the remote 
daemon should run\n [arglist]  = Optional arguments that should be 
passed to the command.  Multiple\n              arguments should be 
separated by a space.  If provided, this must be\n              the last 
option supplied on the command line.\n -h,--help    Print this short 
help.\n -l,--license Print licensing information.\n -n,--no-ssl  Do not 
initial an ssl handshake with the server, talk in 
plaintext.\n\nNote:\nThis plugin requires that you have the NRPE daemon 
running on the remote host.\nYou must also have configured the daemon to 
associate a specific plugin command\nwith the [command] option you are 
specifying here.  Upon receipt of the\n[command] argument, the NRPE 
daemon will run the appropriate plugin command and\nsend the plugin 
output and return code back to *this* plugin.  This allows you\nto 
execute plugins on remote hosts and 'fake' the results to make Nagios 
think\nthe plugin is being run locally.\n\n

so that seems to me as if NRPE does not understand arguments from 
check_nrpe or something...

any ideas?

--
best regards,
yuris


Greg Pangrazio wrote:
> I had a very similar problem with checks coming from Ubuntu 8.04 and
> 10.04 destined for RHEL.  I had to disable SSL on both ends and set
> the encryption method to 0.
>
> I would also check the NRPE config to make sure the passphrases match
> if you are using them.
>
>
> Greg Pangrazio
>
>
>
>
>
> On Thu, Jul 1, 2010 at 6:49 AM, Julius Kidubuka <juki.emma at gmail.com> wrote:
>   
>> Yuris,
>>
>> You could try compiling nrpe without ssl and then in your commands.cfg file
>> have something like this;
>>
>> # 'check_nrpe' command definition
>> define command{
>>         command_name    check_nrpe_no_ssl
>>         command_line    $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$ -n
>>         }
>>
>> Then in your specific service definitions have the check_command line read;
>>
>>  check_command                   check_nrpe_no_ssl!<put-whatever-plugin>
>>
>>
>> Hope this helps.
>>
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>>     


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