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Monitor Linux Debian with NRPE


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Hello to all,

My company is currently migrating the monitoring of our infrastructure from Nagios to Centreon. We have already migrated a lot of Windows and we are still continuing. 
We will soon start the Linux. All our Linux servers are in Debian 10/11. For the moment, we have not yet found a Centreon-NRPE agent for Debian machines. I have the impression that the agent has been developed for CentOS or RedHat. Have you ever done monitoring via NRPE on Debian or Ubuntu systems?

Thanks in advance for your answers which would be a great help!

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Best answer by Kriko 30 May 2022, 10:02

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11 replies

Userlevel 6
Badge +19

Hi @Captain_Adam 

 

You can use the one coming by default from Debian repositories. You have to modify the configuration file afterwards with the one shipped with the CentOS/Redhat RPM. 

 

We will probably build a deb package but I’m not sure about when. 

 

Kind regards,

Badge +2

Thank you sims24 !

But when I search for centreon-nrpe, I get no results. Is there a repository to add to install this package? 

Userlevel 6
Badge +19

I think the package name is nagios-nrpe-server: 

 

apt-get install nagios-nrpe-server

Badge +2

Hello sims24,

 

Sorry for the late reply, I just started working on my Centreon project again. 

I found the nagios-nrpe-server package for Debian. I also took the conf file from the package on CentOS. The problem is not totally solved. Indeed, when I execute an NRPE request from my Centreon server to my monitorer server, an error appears on the terminal : 

 

CHECK_NRPE: Receive header underflow - only 0 bytes received (4 expected).

 

Do you have an idea on how to solve the problem?

If you have any ideas, don't hesitate!

Badge +2

Hello :)

I just noticed something important. For the execution of the centreon-plugins.pl file, it is necessary to have installed the different Perl dependencies. Unfortunately, many of these dependencies do not exist in the Debian repos.

Did you manage to use the "centreon-plugins.pl" on Debian?

Userlevel 5
Badge +16

Hello Captain o7

I just done a quick test with a fresh install of Debian and git clone of the repo.

And I didn’t get any perl error dependencies for the basic mode.

here the perl package installed on my Debian:

root@debian:/opt# dpkg -l | grep -i perl
ii liberror-perl 0.17029-1 all Perl module for error/exception handling in an OO-ish way
ii liblocale-gettext-perl 1.07-4+b1 amd64 module using libc functions for internationalization in Perl
ii libpcre2-8-0:amd64 10.36-2 amd64 New Perl Compatible Regular Expression Library- 8 bit runtime files
ii libpcre3:amd64 2:8.39-13 amd64 Old Perl 5 Compatible Regular Expression Library - runtime files
ii libperl5.32:amd64 5.32.1-4+deb11u2 amd64 shared Perl library
ii libtext-charwidth-perl 0.04-10+b1 amd64 get display widths of characters on the terminal
ii libtext-iconv-perl 1.7-7+b1 amd64 module to convert between character sets in Perl
ii libtext-wrapi18n-perl 0.06-9 all internationalized substitute of Text::Wrap
ii perl 5.32.1-4+deb11u2 amd64 Larry Wall's Practical Extraction and Report Language
ii perl-base 5.32.1-4+deb11u2 amd64 minimal Perl system
ii perl-modules-5.32 5.32.1-4+deb11u2 all Core Perl modules

 

Userlevel 5
Badge +16

About the error of nrpe.
Do you have any message server side ? /var/log/syslog ?

What is the exact command executed from centreon ?

Badge +2

Hi Kriko ! 

 

This is my syslog file when i launch a command from my Centreon Central (with centreon_plugins) : 

 

May 25 15:15:04 SRV-FOG nrpe[895]: Allowing connections from: 127.0.0.1,192.168.31.14
May 25 15:15:11 SRV-FOG nrpe[918]: Error: Request contained command arguments!
May 25 15:15:11 SRV-FOG nrpe[918]: Client request from 192.168.31.14 was invalid, bailing out...
May 25 15:15:32 SRV-FOG nrpe[922]: Error: (!log_opts) Could not complete SSL handshake with 192.168.31.14: 1
May 25 15:15:39 SRV-FOG nrpe[926]: Error: (!log_opts) Could not complete SSL handshake with 192.168.31.14: 1
May 25 15:16:12 SRV-FOG nrpe[931]: Error: (!log_opts) Could not complete SSL handshake with 192.168.31.14: 1

 

This is my nrpe.cfg on my debian server :

As you can see, I have allowed the arguments

#############################################################################
#
# Sample NRPE Config File
#
# Notes:
#
# This is a sample configuration file for the NRPE daemon. It needs to be
# located on the remote host that is running the NRPE daemon, not the host
# from which the check_nrpe client is being executed.
#
#############################################################################


# LOG FACILITY
# The syslog facility that should be used for logging purposes.

log_facility=daemon



# LOG FILE
# If a log file is specified in this option, nrpe will write to
# that file instead of using syslog.

#log_file=/var/log/nrpe.log



# DEBUGGING OPTION
# This option determines whether or not debugging messages are logged to the
# syslog facility.
# Values: 0=debugging off, 1=debugging on

debug=0



# PID FILE
# The name of the file in which the NRPE daemon should write it's process ID
# number. The file is only written if the NRPE daemon is started by the root
# user and is running in standalone mode.

pid_file=/var/run/nagios/nrpe.pid



# PORT NUMBER
# Port number we should wait for connections on.
# NOTE: This must be a non-privileged port (i.e. > 1024).
# NOTE: This option is ignored if NRPE is running under either inetd or xinetd

server_port=5666



# SERVER ADDRESS
# Address that nrpe should bind to in case there are more than one interface
# and you do not want nrpe to bind on all interfaces.
# NOTE: This option is ignored if NRPE is running under either inetd or xinetd

#server_address=127.0.0.1



# LISTEN QUEUE SIZE
# Listen queue size (backlog) for serving incoming connections.
# You may want to increase this value under high load.

#listen_queue_size=5



# NRPE USER
# This determines the effective user that the NRPE daemon should run as.
# You can either supply a username or a UID.
#
# NOTE: This option is ignored if NRPE is running under either inetd or xinetd

nrpe_user=nagios



# NRPE GROUP
# This determines the effective group that the NRPE daemon should run as.
# You can either supply a group name or a GID.
#
# NOTE: This option is ignored if NRPE is running under either inetd or xinetd

nrpe_group=nagios



# ALLOWED HOST ADDRESSES
# This is an optional comma-delimited list of IP address or hostnames
# that are allowed to talk to the NRPE daemon. Network addresses with a bit mask
# (i.e. 192.168.1.0/24) are also supported. Hostname wildcards are not currently
# supported.
#
# Note: The daemon only does rudimentary checking of the client's IP
# address. I would highly recommend adding entries in your /etc/hosts.allow
# file to allow only the specified host to connect to the port
# you are running this daemon on.
#
# NOTE: This option is ignored if NRPE is running under either inetd or xinetd

allowed_hosts=127.0.0.1,192.168.31.14



# 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



# BASH COMMAND SUBSTITUTION
# This option determines whether or not the NRPE daemon will allow clients
# to specify arguments that contain bash command substitutions of the form
# $(...). This option only works if the daemon was configured with both
# the --enable-command-args and --enable-bash-command-substitution configure
# script options.
#
# *** ENABLING THIS OPTION IS A HIGH SECURITY RISK! ***
# Read the SECURITY file for information on some of the security implications
# of enabling this variable.
#
# Values: 0=do not allow bash command substitutions,
# 1=allow bash command substitutions

allow_bash_command_substitution=1



# COMMAND PREFIX
# This option allows you to prefix all commands with a user-defined string.
# A space is automatically added between the specified prefix string and the
# command line from the command definition.
#
# *** THIS EXAMPLE MAY POSE A POTENTIAL SECURITY RISK, SO USE WITH CAUTION! ***
# Usage scenario:
# Execute restricted commmands using sudo. For this to work, you need to add
# the nagios user to your /etc/sudoers. An example entry for allowing
# execution of the plugins from might be:
#
# nagios ALL=(ALL) NOPASSWD: /usr/lib/nagios/plugins/
#
# This lets the nagios user run all commands in that directory (and only them)
# without asking for a password. If you do this, make sure you don't give
# random users write access to that directory or its contents!

# command_prefix=/usr/bin/sudo


# MAX COMMANDS
# This specifies how many children processes may be spawned at any one
# time, essentially limiting the fork()s that occur.
# Default (0) is set to unlimited
# max_commands=0



# COMMAND TIMEOUT
# This specifies the maximum number of seconds that the NRPE daemon will
# allow plugins to finish executing before killing them off.

command_timeout=60



# CONNECTION TIMEOUT
# This specifies the maximum number of seconds that the NRPE daemon will
# wait for a connection to be established before exiting. This is sometimes
# seen where a network problem stops the SSL being established even though
# all network sessions are connected. This causes the nrpe daemons to
# accumulate, eating system resources. Do not set this too low.

connection_timeout=300



# WEAK RANDOM SEED OPTION
# This directive allows you to use SSL even if your system does not have
# a /dev/random or /dev/urandom (on purpose or because the necessary patches
# were not applied). The random number generator will be seeded from a file
# which is either a file pointed to by the environment valiable $RANDFILE
# or $HOME/.rnd. If neither exists, the pseudo random number generator will
# be initialized and a warning will be issued.
# Values: 0=only seed from /dev/[u]random, 1=also seed from weak randomness

#allow_weak_random_seed=1

# SSL/TLS OPTIONS
# These directives allow you to specify how to use SSL/TLS.

# SSL VERSION
# This can be any of: SSLv2 (only use SSLv2), SSLv2+ (use any version),
# SSLv3 (only use SSLv3), SSLv3+ (use SSLv3 or above), TLSv1 (only use
# TLSv1), TLSv1+ (use TLSv1 or above), TLSv1.1 (only use TLSv1.1),
# TLSv1.1+ (use TLSv1.1 or above), TLSv1.2 (only use TLSv1.2),
# TLSv1.2+ (use TLSv1.2 or above)
# If an "or above" version is used, the best will be negotiated. So if both
# ends are able to do TLSv1.2 and use specify SSLv2, you will get TLSv1.2.
# If you are using openssl 1.1.0 or above, the SSLv2 options are not available.

#ssl_version=SSLv2+

# SSL USE ADH
# This is for backward compatibility and is DEPRECATED. Set to 1 to enable
# ADH or 2 to require ADH. 1 is currently the default but will be changed
# in a later version.

#ssl_use_adh=1

# SSL CIPHER LIST
# This lists which ciphers can be used. For backward compatibility, this
# defaults to 'ssl_cipher_list=ALL:!MD5:@STRENGTH' for < OpenSSL 1.1.0,
# and 'ssl_cipher_list=ALL:!MD5:@STRENGTH:@SECLEVEL=0' for OpenSSL 1.1.0 and
# greater.

#ssl_cipher_list=ALL:!MD5:@STRENGTH
#ssl_cipher_list=ALL:!MD5:@STRENGTH:@SECLEVEL=0
#ssl_cipher_list=ALL:!aNULL:!eNULL:!SSLv2:!LOW:!EXP:!RC4:!MD5:@STRENGTH

# SSL Certificate and Private Key Files

#ssl_cacert_file=/etc/ssl/servercerts/ca-cert.pem
#ssl_cert_file=/etc/ssl/servercerts/nagios-cert.pem
#ssl_privatekey_file=/etc/ssl/servercerts/nagios-key.pem

# SSL USE CLIENT CERTS
# This options determines client certificate usage.
# Values: 0 = Don't ask for or require client certificates (default)
# 1 = Ask for client certificates
# 2 = Require client certificates

#ssl_client_certs=0

# SSL LOGGING
# This option determines which SSL messages are send to syslog. OR values
# together to specify multiple options.

# Values: 0x00 (0) = No additional logging (default)
# 0x01 (1) = Log startup SSL/TLS parameters
# 0x02 (2) = Log remote IP address
# 0x04 (4) = Log SSL/TLS version of connections
# 0x08 (8) = Log which cipher is being used for the connection
# 0x10 (16) = Log if client has a certificate
# 0x20 (32) = Log details of client's certificate if it has one
# -1 or 0xff or 0x2f = All of the above

#ssl_logging=0x00



# NASTY METACHARACTERS
# This option allows you to override the list of characters that cannot
# be passed to the NRPE daemon.

# nasty_metachars="|`&><'\\[]{};\r\n"



# COMMAND DEFINITIONS
# Command definitions that this daemon will run. Definitions
# are in the following format:
#
# command[<command_name>]=<command_line>
#
# When the daemon receives a request to return the results of <command_name>
# it will execute the command specified by the <command_line> argument.
#
# Unlike Nagios, the command line cannot contain macros - it must be
# typed exactly as it should be executed.
#
# Note: Any plugins that are used in the command lines must reside
# on the machine that this daemon is running on! The examples below
# assume that you have plugins installed in a /usr/local/nagios/libexec
# directory. Also note that you will have to modify the definitions below
# to match the argument format the plugins expect. Remember, these are
# examples only!


# The following examples use hardcoded command arguments...
# This is by far the most secure method of using NRPE

command[check_users]=/usr/lib/nagios/plugins/check_users -w 5 -c 10
command[check_load]=/usr/lib/nagios/plugins/check_load -r -w .15,.10,.05 -c .30,.25,.20
command[check_hda1]=/usr/lib/nagios/plugins/check_disk -w 20% -c 10% -p /dev/hda1
command[check_zombie_procs]=/usr/lib/nagios/plugins/check_procs -w 5 -c 10 -s Z
command[check_total_procs]=/usr/lib/nagios/plugins/check_procs -w 150 -c 200
command[check_centreon_plugins]=/usr/lib/centreon/plugins/centreon_plugins.pl --plugin=$ARG1$ --mode=$ARG2$ $ARG3$

# The following examples allow user-supplied arguments and can
# only be used if the NRPE daemon was compiled with support for
# command arguments *AND* the dont_blame_nrpe directive in this
# config file is set to '1'. This poses a potential security risk, so
# make sure you read the SECURITY file before doing this.

### MISC SYSTEM METRICS ###
#command[check_users]=/usr/lib/nagios/plugins/check_users $ARG1$
#command[check_load]=/usr/lib/nagios/plugins/check_load $ARG1$
#command[check_disk]=/usr/lib/nagios/plugins/check_disk $ARG1$
#command[check_swap]=/usr/lib/nagios/plugins/check_swap $ARG1$
#command[check_cpu_stats]=/usr/lib/nagios/plugins/check_cpu_stats.sh $ARG1$
#command[check_mem]=/usr/lib/nagios/plugins/custom_check_mem -n $ARG1$

### GENERIC SERVICES ###
#command[check_init_service]=sudo /usr/lib/nagios/plugins/check_init_service $ARG1$
#command[check_services]=/usr/lib/nagios/plugins/check_services -p $ARG1$

### SYSTEM UPDATES ###
#command[check_yum]=/usr/lib/nagios/plugins/check_yum
#command[check_apt]=/usr/lib/nagios/plugins/check_apt

### PROCESSES ###
#command[check_all_procs]=/usr/lib/nagios/plugins/custom_check_procs
#command[check_procs]=/usr/lib/nagios/plugins/check_procs $ARG1$

### OPEN FILES ###
#command[check_open_files]=/usr/lib/nagios/plugins/check_open_files.pl $ARG1$

### NETWORK CONNECTIONS ###
#command[check_netstat]=/usr/lib/nagios/plugins/check_netstat.pl -p $ARG1$ $ARG2$

### ASTERISK ###
#command[check_asterisk]=/usr/lib/nagios/plugins/check_asterisk.pl $ARG1$
#command[check_sip]=/usr/lib/nagios/plugins/check_sip $ARG1$
#command[check_asterisk_sip_peers]=sudo /usr/lib/nagios/plugins/check_asterisk_sip_peers.sh $ARG1$
#command[check_asterisk_version]=/usr/lib/nagios/plugins/nagisk.pl -c version
#command[check_asterisk_peers]=/usr/lib/nagios/plugins/nagisk.pl -c peers
#command[check_asterisk_channels]=/usr/lib/nagios/plugins/nagisk.pl -c channels
#command[check_asterisk_zaptel]=/usr/lib/nagios/plugins/nagisk.pl -c zaptel
#command[check_asterisk_span]=/usr/lib/nagios/plugins/nagisk.pl -c span -s 1



# INCLUDE CONFIG FILE
# This directive allows you to include definitions from an external config file.

#include=<somefile.cfg>



# INCLUDE CONFIG DIRECTORY
# This directive allows you to include definitions from config files (with a
# .cfg extension) in one or more directories (with recursion).

#include_dir=<somedirectory>
#include_dir=<someotherdirectory>



# local configuration:
# if you'd prefer, you can instead place directives here

include=/etc/nagios/nrpe_local.cfg

# you can place your config snipplets into nrpe.d/
# only snipplets ending in .cfg will get included

include_dir=/etc/nagios/nrpe.d/

 

Userlevel 5
Badge +16

Here the issue: 

May 25 15:15:11 SRV-FOG nrpe[918]: Error: Request contained command arguments!
May 25 15:15:11 SRV-FOG nrpe[918]: Client request from 192.168.31.14 was invalid, bailing out...

After some “investigation” on the internet, it seems that the maintener of the package doesn’t allow the usage of arguments:

https://serverfault.com/questions/996115/nagios-nrpe-wont-allow-arguments

  * [023e909] Disable command-args in nrpe. (Closes: #745272) from (https://metadata.ftp-master.debian.org/changelogs//main/n/nagios-nrpe/nagios-nrpe_3.0.1-3+deb9u1_changelog)

I guess that you need to compile the daemon with the option to enable args.

Badge +2

Hi Kriko,

 

I comeback with good news ! 

I have reinstall the nrpe on my Debian with the tar.gz file from the nagios official site.

It’s work ! I created a bash script to avoid having problems again !

Thanks for your help anyway :)

Userlevel 5
Badge +16

You’re welcome o/

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