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UNIX / Nagios server not talking

Posted: Tue Jan 03, 2012 8:01 am
by fao
Dear All,

we installed recently Nagios on both our UNIX and Linux servers.

While Linux client data streaming toward Nagios server is working more or less flawlessly, when the NRPE is on UNIX servers the data streaming does NOT work and Nagios can't collect data and perform any monitoring.

Nagios NRPE version is:

UNIX OS Version is: HP UX 11.31 (Itanium)

The nrpe.conf is the following:

Code: Select all

==============================================================
#############################################################################
# Sample NRPE Config File 
# Written by: Ethan Galstad ([email protected])
# 
# Last Modified: 11-23-2007
#
# 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



# 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/nrpe.pid



# PORT NUMBER
# Port number we should wait for connections on.
# NOTE: This must be a non-priviledged 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



# 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.
#
# 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,xxxx.xxx.xxx.xxx
allowed_hosts=127.0.0.1
 


# 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



# 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 alllowing 
# 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 



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

debug=1



# 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



# WEEK 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



# 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>



# 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...

command[check_users]=/opt/iexpress/nagios/libexec/check_users -w 5 -c 10
command[check_load]=/opt/iexpress/nagios/libexec/check_load -w 15,10,5 -c 30,25,20
command[check_hpux_disk]=/opt/iexpress/nagios/libexec/check_disk -w 20 -c 10
command[check_zombie_procs]=/opt/iexpress/nagios/libexec/check_procs -w 5 -c 10 -s Z
command[check_total_procs]=/opt/iexpress/nagios/libexec/check_procs -w 150 -c 200 
command[check_swap]=/opt/iexpress/nagios/libexec/check_swap -w 20 -c 10
command[check_ping]=/opt/iexpress/nagios/libexec/check_ping -H 127.0.0.1 -w 100.0,20% -c 500.0,60%

# 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.

#command[check_users]=/opt/iexpress/nagios/libexec/check_users -w $ARG1$ -c $ARG2$
#command[check_load]=/opt/iexpress/nagios/libexec/check_load -w $ARG1$ -c $ARG2$
#command[check_disk]=/opt/iexpress/nagios/libexec/check_disk -w $ARG1$ -c $ARG2$ -p $ARG3$
#command[check_procs]=/opt/iexpress/nagios/libexec/check_procs -w $ARG1$ -c $ARG2$ -s $ARG3$
==============================================================
Please notice that for security reasons we did not enable Nagios to pass parameters to HP UX server, but we directly called only the NRPE scripts.

Further: the connection test between Nagios and NRPE is positive.

Any advice?

Thanks in advance

Re: UNIX / Nagios server not talking

Posted: Tue Jan 03, 2012 8:33 am
by fao
NRPE Version is:

NRPE Plugin for Nagios
Copyright (c) 1999-2008 Ethan Galstad ([email protected])
Version: 2.12

Re: UNIX / Nagios server not talking

Posted: Tue Jan 03, 2012 10:45 am
by lmiltchev
fao,

take a look at the "# ALLOWED HOST ADDRESSES" section - you have:

Code: Select all

#allowed_hosts=127.0.0.1,xxxx.xxx.xxx.xxx
allowed_hosts=127.0.0.1
Your Nagios server IP address should be listed on the bottom line (the one that is not commented out), UNLESS you are using xinetd instead.

Hope this helps.

Re: UNIX / Nagios server not talking

Posted: Tue Jan 03, 2012 4:41 pm
by niebais
How big is the performance data coming back from the Linux system? Sometimes you can send it too much information and it will chop off the performance data. I believe the default is 1024.

Re: UNIX / Nagios server not talking

Posted: Wed Jan 04, 2012 9:04 am
by fao
lmiltchev wrote:fao,

take a look at the "# ALLOWED HOST ADDRESSES" section - you have:

Code: Select all

#allowed_hosts=127.0.0.1,xxxx.xxx.xxx.xxx
allowed_hosts=127.0.0.1
Your Nagios server IP address should be listed on the bottom line (the one that is not commented out), UNLESS you are using xinetd instead.

Hope this helps.
xinetd has been used. Is this meaning that I can omit presenting the Nagios server IP address in the nrpe.cfg?

Re: UNIX / Nagios server not talking

Posted: Wed Jan 04, 2012 10:18 am
by lmiltchev
Yes, you can omit the Nagios server IP address in the nrpe.cfg file if you are using xinetd. However, the IP must be listed in: /etc/xinet/nrpe in the "only_from" line, for example:

Code: Select all

only_from   = 127.0.0.1 192.168.X.XX
If it is not listed there, you need to add it and restart the daemon:

Code: Select all

# service xinetd restart
Also, make sure port 5666 is open and there are no firewall issues.

Re: UNIX / Nagios server not talking

Posted: Wed Jan 04, 2012 10:35 am
by fao
It is inside the LAN, so firewall should be not an issue.

Thanks, I am going to check it.

Re: UNIX / Nagios server not talking

Posted: Wed Jan 04, 2012 11:35 am
by fao
lmiltchev wrote:Yes, you can omit the Nagios server IP address in the nrpe.cfg file if you are using xinetd. However, the IP must be listed in: /etc/xinet/nrpe in the "only_from" line, for example:

Code: Select all

only_from   = 127.0.0.1 192.168.X.XX
If it is not listed there, you need to add it and restart the daemon:

Code: Select all

# service xinetd restart
Also, make sure port 5666 is open and there are no firewall issues.
You're mentioning Linux settings.

I am currently working on a HP UX Unix server: xinetd is NOT existing in UNIX, but exist inetd

Re: UNIX / Nagios server not talking

Posted: Wed Jan 04, 2012 11:47 am
by mguthrie
We don't have much documented for NRPE and Unix, although it is in the works. With NRPE on any system, a few things need to be in place for it to work.

#1 The firewall needs to accept incoming connections on port 5666 from either any address or a range of addresses.
#2 Either the NRPE daemon, or the daemon that it's running under needs to be able to accept a command from an incoming IP address that is specified in the allowed_hosts directive.
#3 If there is still an issue beyond that, then it could be related to SSL. I don't know what the Unix equivalents of the packages openssl and openssl-devel, but those are required on Linux installs for it to work correctly.

Re: UNIX / Nagios server not talking

Posted: Wed Jan 04, 2012 11:48 am
by niebais
What package did you use to install NRPE? We have several HPUX systems where I work and we monitor them with NRPE. Did you compile NRPE?

I'll see if I can find some documentation on the NRPE package. I know that HPUX has some special requirements when you compile it, otherwise it fails to work unless you use the --no-ssl option.