Error: Nagios/Icinga (Debian Squeeze) - CHECK_NRPE: Received 0 bytes from daemon. Check the remote server logs for error messages.

You monitor a remote server with Nagios or Icinga and see the following error in your Nagios/Icinga web interface:

CHECK_NRPE: Received 0 bytes from daemon. Check the remote server logs for error messages.

In /var/log/syslog on the remote server you see these messages:

Aug 23 14:20:20 server2 nrpe[11496]: Error: Request contained command arguments, but argument option is not enabled!
Aug 23 14:20:20 server2 nrpe[11496]: Client request was invalid, bailing out...

 

Solution

Open /etc/nagios/nrpe.cfg on the remote Nagios NRPE server...

vi /etc/nagios/nrpe.cfg

... and set dont_blame_nrpe to 1:

[...]
# COMMAND ARGUMENT PROCESSING
# This option determines whether or not the NRPE daemon will allow clients
# to specify arguments to commands that are executed.  This option only works
# if the daemon was configured with the --enable-command-args configure script
# option.
#
# *** ENABLING THIS OPTION IS A SECURITY RISK! ***
# Read the SECURITY file for information on some of the security implications
# of enabling this variable.
#
# Values: 0=do not allow arguments, 1=allow command arguments

dont_blame_nrpe=1
[...]

Save the file and restart the NRPE server:

/etc/init.d/nagios-nrpe-server restart

Falko Timme

About Falko Timme

Falko Timme is an experienced Linux administrator and founder of Timme Hosting, a leading nginx business hosting company in Germany. He is one of the most active authors on HowtoForge since 2005 and one of the core developers of ISPConfig since 2000. He has also contributed to the O'Reilly book "Linux System Administration".

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By: robbyb

There is another possible reason for the above error:

If all is configured as above AND a nagios command configured like

command_line    $USER1$/check_nrpe -H $HOSTADDRESS$ -t 60 -c $ARG1$ -a "$ARG2$"

AND a concrete check_command is configured like

 check_command                   check_nrpe!check_apt

WITHOUT a second argument to propagated to the -a option the above error occurs in nrpe version 2.15. In version 2.13 the check would be ok.

A solution is to configure 2 nagios commands one with and one without the commandline switch -a.