3 - installation - nrpe client (centos 6.5) - how to - gutzmann gmbh.pdf

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tallation - NRPE Client (CentOS 6.5) - How To - Gutzmann GmbH

/wiki.gutzmann.com/confluence/pages/viewpage.action?pageId=12681241[11/09/2014 11:53:43 CH]

3 - Installation - NRPE Client (CentOS 6.5)

References

Prepare system

/etc/hosts

/etc/sysconfig/network

/etc/services

/etc/resolv.conf

Install latest updates

Install prerequisites

Start NTP

Start XINETD

Add Users and groupsApache

Firewall settings

Download Nagios and related software

Install Nagios Plugins

Install and setup NRPE

Install NRPE client

Configure xinetd

Restrict access to Nagios server

Set up logging

Test NRPE locally

Customize NRPE commands

Test NRPE from the Nagios monitoring server

References

Nagios: http://assets.nagios.com/downloads/nagioscore/docs/Installing_Nagios_Core_From_Source.pdf

NRPE: http://nagios.sourceforge.net/docs/nrpe/NRPE.pdf

Prepare system

/etc/hosts

The host table must include information about the current host, for example

10. 3. 1. 16 wi ki - uh. gut zmann. com wi ki

/etc/sysconfig/network

The hostname should be set up accordingly in / et c/ sysconf i g/ net work:

HOSTNAME="wi ki . gut zmann. com"

/etc/services

Add the NRPE port to /etc/services:

vi / etc/ servi ces

locate "5671" and insert before:

Created by Thomas Gutzmann, last modified on 2014-04-22

Dashboard

ToolsHow To

Dashboard Public How To Pages Nagios - Transcripts
http://assets.nagios.com/downloads/nagioscore/docs/Installing_Nagios_Core_From_Source.pdfhttp://nagios.sourceforge.net/docs/nrpe/NRPE.pdfhttps://wiki.gutzmann.com/confluence/display/~gutzmthohttps://wiki.gutzmann.com/confluence/pages/diffpagesbyversion.action?pageId=12681241&selectedPageVersions=15&selectedPageVersions=16https://wiki.gutzmann.com/confluence/display/HowTohttps://wiki.gutzmann.com/confluence/dashboard.actionhttps://wiki.gutzmann.com/confluence/dashboard.actionhttps://wiki.gutzmann.com/confluence/category/sub-dashboard.action?categoryKey=publichttps://wiki.gutzmann.com/confluence/category/sub-dashboard.action?categoryKey=publichttps://wiki.gutzmann.com/confluence/display/HowTohttps://wiki.gutzmann.com/confluence/display/HowTohttps://wiki.gutzmann.com/confluence/collector/pages.action?key=HowTohttps://wiki.gutzmann.com/confluence/collector/pages.action?key=HowTohttps://wiki.gutzmann.com/confluence/display/HowTo/Nagios+-+Transcriptshttps://wiki.gutzmann.com/confluence/display/HowTo/Nagios+-+Transcriptshttps://wiki.gutzmann.com/confluence/collector/pages.action?key=HowTohttps://wiki.gutzmann.com/confluence/display/HowTohttps://wiki.gutzmann.com/confluence/category/sub-dashboard.action?categoryKey=publichttps://wiki.gutzmann.com/confluence/dashboard.actionhttps://wiki.gutzmann.com/confluence/display/HowTohttps://wiki.gutzmann.com/confluence/pages/diffpagesbyversion.action?pageId=12681241&selectedPageVersions=15&selectedPageVersions=16https://wiki.gutzmann.com/confluence/display/~gutzmthohttp://nagios.sourceforge.net/docs/nrpe/NRPE.pdfhttp://assets.nagios.com/downloads/nagioscore/docs/Installing_Nagios_Core_From_Source.pdfhttps://wiki.gutzmann.com/confluence/homepage.actionhttps://wiki.gutzmann.com/confluence/homepage.action


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nrpe 5666/ t cp # NRPE

/etc/resolv.conf

Out of context: You should consider using a fast DNS server. I found that Google DNS is much faster than those of

most hosting providers.

vi / etc/ resol v. conf

Insert the line

nameser ver 8. 8. 8. 8before all other nameserver directives.

Install latest updates

yum updat e

Install prerequisites

Some of the packages may already have been installed. If during the installation on your particular server you find a

other missing packages, please be so kind to add a comment to this post.

yum i nst al l bi nd- ut i l s php nt p xi netd openssl - devel make gcc wget

Make sure that Perl is installed by typing "per l - v ". If it's missing, add it by:

yum i nstal l per l

Start NTP

It's important that all servers show the correct time:

servi ce nt pd start

chkconf i g nt pd on

If the system is running on a virtual machine, NTP may fail with the following error message in /var/log/messages:

cap_set_proc() failed to drop root privileges: Operation not permitted

See herehow to handle this problem.

Start XINETD

Check if xinetd is running and start it otherwise:

servi ce xi net d status

If not running:

servi ce xi net d st ar t

Add Users and groups

useradd nagi os

gr oupadd nagcmd

user mod - a - G nagcmd nagi os

Apache

If Apache is installed on the client and you want to have it monitored, make sure that an "index.html" exists:

t ouch / var / www/ html / i ndex. html

Firewall settings
https://wiki.gutzmann.com/confluence/display/HowTo/NTPD+-+cap_set_proc%28%29+failed+to+drop+root+privileges%3A+Operation+not+permittedhttps://wiki.gutzmann.com/confluence/display/HowTo/NTPD+-+cap_set_proc%28%29+failed+to+drop+root+privileges%3A+Operation+not+permitted


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Consider setting up your firewall for dynamic DNSnames.

Add the following line to /etc/sysconfig/iptables, replacing the monitoring server name as required:

vi / etc/ sysconf i g/ i ptabl es

- A I NPUT - m st at e - - st at e NEW - m t cp - p t cp - s moni t or - a. gut zmann. com - - dport 5666 - j

ACCEPT

Restart the firewall:

servi ce i pt abl es r estart

Download Nagios and related software

Install Nagios Plugins

cd / t mp/ nagi os-pl ugi ns- *

. / conf i gure - - wi t h- nagi os- user=nagi os - - wi t h- nagi os- gr oup=nagi os

make

make i nstal l

Install and setup NRPE

Install NRPE client

cd / t mp/ nr pe- *

. / conf i gure

make al l

make i nstal l - pl ugi n

make i nst al l - daemon

make i nst al l - daemon- conf i g

make i nstal l - xi net d

Configure xinetd

Restrict access to Nagios server

vi / etc/ xi netd. d/ nrpe

locate the line starting with "only_from" and append the address(es) of the Nagios monitoring server(s). In this

example we are using 81.20.136.81.

IPv4 only:

onl y_f r om = 127. 0. 0. 1 10. 3. 1. 14

IPv4 and IPv6:

onl y_fr om = 127. 0. 0. 1 81. 20. 136. 81 : : f f f f : 10. 3. 1. 14

Make sure the nrpe daemon is running under xinetd:

net st at - at | gr ep nrpe

The output out this command should show something like this:

t cp 0 0 *: nr pe *: * LI STEN

If you don't see this output, try to restart XINETD:

servi ce xi net d r est ar t

If the test still fails, check / var / l og/ messages.

Check at websites below for more recent versions.
https://wiki.gutzmann.com/confluence/display/HowTo/IPTables+Firewall+Setup+for+Dynamic+DNShttps://wiki.gutzmann.com/confluence/display/HowTo/IPTables+Firewall+Setup+for+Dynamic+DNS


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Set up logging

Make sure that xinetd writes to its own log file, so it doesn't clutter /var/log/messages.

vi / et c/ xi net d. conf

locate the line defining "log_type", and replace it by

l og_t ype = FI LE / var / l og/ xi net dl og

Test NRPE locally

Next, check to make sure the NRPE daemon is functioning properly. To do this, run the check_nrpe plugin that was

installed for testing purposes.

/ usr/ l ocal / nagi os/ l i bexec/ check_nrpe - H 127. 0. 0. 1

You should get a string back that tells you what version of NRPE is installed, like this:

NRPE v2. 15

Customize NRPE commands

Add commands to NRPE by editing /usr/local/nagios/etc/nrpe.cfg. Here is an example:

vi / usr / l ocal / nagi os/ etc/ nrpe. cfg

locate the sections listing NRPE commands and add:

command[ check_root] =/ usr / l ocal / nagi os/ l i bexec/ check_di sk - w 20% - c 10% - p /

command[check_home]=/ usr/ l ocal / nagi os/ l i bexec/ check_di sk - w 20% - c 10% - p / home

Now test the new commands:

/ usr / l ocal / nagi os/ l i bexec/ check_nr pe - H 127. 0. 0. 1 - c check_home

Test NRPE from the Nagios monitoring server

At your Nagios monitoring server (not the one you're running this installation!), run the following command, replacin

"wiki.gutzmann.com" with the name of the actual client server:

/ usr/ l ocal / nagi os/ l i bexec/ check_nrpe -H 10. 3. 1. 17 - c check_l oad

If you see an error message indicating that check_nrpe was not found, check that you didn't miss the definition on t

command in /usr/local/nagios/etc/objects/commands.cfg; see "1 - Installation - Nagios Server (CentOS 6.4)".

If you see the error message "CHECK_NRPE: Error - Could not complete SSL handshake.", you should check:

Went something wrong with the firewall configuration? Try "t el net 10. 3. 1. 17 5666" from the Nagios

server (replace the IP name with the name or address of your NRPE client). Enter "QUIT" do stop the telnet

session (there are more correct ways, but this will do).

Check all configuration files if you accidentally entered sample data from this How-To.

Make sure that you actually testing from the Nagios monitoring server and not from the host you just installed

NRPE Client on. Reason is that you didn't allow the client's public IP address in /etc/xinet.d/nrpe, just localho

and the Nagios server.

No lab

For comments and questions please contact wikigutzmann.com.

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