linux network server group: nagios

M. Bechtel, S. Blümel, A. Quignon 1

Linux Network ServerGroup: Nagios

Marc Bechtel

Sebastian Blümel

Alexandre Quignon


Table of Contents

1. Overview

2. Requirements (MYSQL, APACHE, CONFIGS…)

3. A short introduction to Nagios

4. Nagios-Configuration with Fruity

5. Installation and Configuration Problems

6. Nagios in Action

7. Nagios with SNMP and Cisco


Requirements

YUM-Installation Manager

MySQL 5.0.4-5

Apache 2.0.52-28

PHP 5.0.4-5

Postfix 2.2.2.10-1

Self installed

Nagios 2.5

Fruity 1 RC 1

./chkconfig --add httpd

./chkconfig --level 235 httpd on

./chkconfig –add mysql

./chkconfig --level 235 mysql on

./chkconfig –add nagios

./chkconfig --level 235 nagios on

6 different runlevels

0 - Halt the system 1 - Single-user mode 2 - Multi-user mode (without NFS) 3 - Multi-user mode 5 - Multi-user mode, graphical login 6 - Reboot the system


Table of Contents

1. Overview

2. Requirements (MYSQL, APACHE, CONFIGS…)

3. A short introduction to Nagios

4. Nagios-Configuration with Fruity

5. Installation and Configuration Problems

6. Nagios in Action

7. Nagios with SNMP and Cisco


What is Nagios?

Nagios is System and network monitoring application

Developed by Ethan Galstad

Formerly know as Netsaint (2002)

Nagios is open source Software (General Public License)

current verion is 2.5

„Nagios is quite powerful and flexible, but unfortunately its not very friendly to newbies. Why? Because it takes a lot of work to get it installed and configured properly. That being said, if you stick with it and manage to get it up and running, you’ll never want to be without it. :-)“


Monitoring of…

Nagios can supervise:

Hosts (Windows, Linux, …) and host resources (Disk Usage, Load)

Services (FTP, Mail, HTTP, …)

SNMP Traps

other hardware devices (like temperature sensors,filling level indicator,…)

In case of emergency send notifications:

email, pager, SMS

any user-defined method through plug-in system


Plug-in concept

How is this achieved?

build in check services (DNS, SNMP, SMTP, ICMP,…)

by simple plug-in design that allows users to easily develop their own service checks

Upside: You can monitor just about anything you can think of!

Downside: Nagios cannot produce graphs of collected data because it has no further information about what you are monitoring!

Check Plugin

Webfrontend

Nagios Deamon

Administrator

Check Status

OK,Warning,Critical

Notification


Configuring Nagios

As all Linux Software Nagios heavily relies on config files!

We will have a (short) look at:

httpd.conf

nagios.cfg

hosts.cfg & hostgroup.cfg

contacts.cfg & contactsgroup.cfg

services.cfg and commands.cfg

Do I have to configure all by hand?


Configuration-Files


Apache: httpd.conf

ScriptAlias /nagios/cgi-bin /usr/local/nagios/sbin

<Directory "/usr/local/nagios/sbin">

Options ExecCgi

AllowOverride AuthConfig

Order allow, deny

Allow from all

</Directory>

Alias /nagios /usr/local/nagios/share

<Directory "/usr/local/nagios/share">

Options ExecCgi

AllowOverride AuthConfig

Order allow, deny

Allow from all

</Directory>

Configure Script Alias For The CGIs: default installation expects to find them accessible at http://yourmachine/nagios/cgi-bin/

Configure Alias For The HTML Files: to make the HTML files accessible via the web server

http://192.168.10.4/nagios


Main Configuration File: nagios.cfg

Location: /usr/local/nagios/etc/nagios.cfg

Refers to all other config files

First file read by the Nagios process

Extract:

log_file=/var/log/nagios/nagios.log

cfg_file=/usr/local/nagios/etc/hosts.cfg

cfg_file=/usr/local/nagios/etc/commands.cfg


host.cfg and hostgroup.cfg

define host {

host_name FTP

alias FTP Server

address 192.168.10.21

check_command Ping

check_period 24x7

contact_groups LNS

}

define hostgroup{

hostgroup_name AllServers

alias all Server

members FTP

}

Description: A host definition is used to define a physical server, workstation, device, etc. that resides on your network.

Description: A host group definition is used to group one or more hosts together for display purposes in the CGIs.


contactgroups.cfg and contacts.cfg

define contactgroup{

contactgroup_name LNS

alias ThisIsATestGroup

members Marc

}

define contact{

contact_name Marc

alias Marc Bechtel

host_notification_period 24x7

host_notification_commands

send_notification_mail_host

email [email protected]

}

Description: A contact group definition is used to group one or more contacts together for the purpose of sending out alert/recovery notifications.

Description:A contact definition is used to identify someone who should be contacted in the event of a problem on your network.


Configuration-Files


services.cfg and commands.cfg

define service {

service_description Ping

check_command Ping

max_check_attempts 2

contact_groups LNS

}

define command{

command_name Ping

command_line /usr/local/nagios/libexec/check_icmp $HOSTADDRESS$ -c 500,10%

}

Description:A service definition is used to identify a "service" that runs on a host.

Description:How to perform a service check.


Verifying Your Nagios Configuration:

Pre-Flight Check with the –v option/usr/local/nagios/bin/nagios -v <main_config_file>

Nagios verifies that you have defined the necessary data relationships for monitoring.

1. Verify that all contacts are a member of at least one contact group.

2. Verify that all contacts specified in each contact group are valid.

3. Verify that all hosts are a member of at least one host group.

4. Verify that all hosts specified in each host group are valid.

5. Verify that all hosts have at least one service associated with them.

…


Table of Contents

Overview

Requirements (MYSQL, APACHE, CONFIGS…)

A short introduction to Nagios

Nagios-Configuration with Fruity

Installation and Configuration Problems

Nagios in Action

Nagios with SNMP and Cisco


Fruity

What is Fruity?

PHP based web-frontend

Open Source project

Why are we using Fruity?

Simplicity

Easy to make changes

No manual *.cfg file handling

Demonstation of Fruity


Table of Contents

Overview





Nagios in Action



Fruity Configuration Problems

SELinux blocking write access for Fruity

File missing:

/usr/local/nagios/objectconf/oconf.cfg

Two processes at shutdown


Table of Contents

Overview





Nagios in Action



Monitoring

What is offered by Nagios ?

Host Monitoring

Service Monitoring

Status Map

3D Map


Reporting

Nagios Standard

Trends

Availability

Alert Diagrams

Notification / Event Log

PNP

Performance Diagrams


Notification

Mail command

Miranda

Mailbox Root


Table of Contents

Overview





Nagios in Action



What’s a MIB

Used to manage devices in a Network

Hierarchical database

All objects are addressed through a OID (Object Identifier)

Is used by SNMP (Simple Network Management Protocol)

There are Standard and Enterprise MIBs

IF-MIB: RFC 2863

IP-MIB: RFC 4293

CISCO-PRODUCTS-MIB: www.cisco.com


Cisco Catalyst 2950 SNMP Check

MIB-II: RFC 1213

OID: 1.3.6.1.2.1.2.2.1.8. <Interface Nr>

Values: 1, 2, 3 (up, down, testing)

Command:

check_snmp -H 192.168.10.150 -o 1.3.6.1.2.1.2.2.1.8.17 -C public -c 1:1


QUESTIONS

linux network server group: nagios

Documents

linux software nagios

multiuser mode

configuration problemsnagios

short introduction

singleuser mode

html files accessible

linux network servergroup

filling level indicator