Linux Network Server Group: Nagios

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Linux Network ServerGroup Nagios
Marc Bechtel Sebastian Blümel Alexandre Quignon
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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

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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
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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

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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, youll never want to be without
  it. -)

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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

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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!

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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?

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Configuration-Files
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Apache httpd.conf

• ScriptAlias /nagios/cgi-bin /usr/local/nagios/sbin
  
• ltDirectory "/usr/local/nagios/sbin"gt
• Options ExecCgi
• AllowOverride AuthConfig
• Order allow, deny
• Allow from all
• lt/Directorygt
• Alias /nagios /usr/local/nagios/share
• ltDirectory "/usr/local/nagios/share"gt
• Options ExecCgi
• AllowOverride AuthConfig
• Order allow, deny
• Allow from all
• lt/Directorygt

• 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

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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

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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.

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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 marcbechtel_at_gmail.com

• Description A contact group definition is used
  to group one or more contacts together for the
  purpose of sending out alert/recovery
  notifications.
• DescriptionA contact definition is used to
  identify someone who should be contacted in the
  event of a problem on your network.

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Configuration-Files
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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_i
  cmp HOSTADDRESS -c 500,10

• DescriptionA service definition is used to
  identify a "service" that runs on a host.
• DescriptionHow to perform a service check.

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Verifying Your Nagios Configuration

• Pre-Flight Check with the v option/usr/local/na
  gios/bin/nagios -v ltmain_config_filegt
• 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.

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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

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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

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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

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Fruity Configuration Problems

• SELinux blocking write access for Fruity
• File missing
• /usr/local/nagios/objectconf/oconf.cfg
• Two processes at shutdown

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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

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Monitoring

• What is offered by Nagios ?
• Host Monitoring
• Service Monitoring
• Status Map
• 3D Map

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Reporting

• Nagios Standard
• Trends
• Availability
• Alert Diagrams
• Notification / Event Log
• PNP
• Performance Diagrams

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Notification
Miranda
Mailbox Root
Mail command
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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

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Whats 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

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Cisco Catalyst 2950 SNMP Check

• MIB-II RFC 1213
• OID 1.3.6.1.2.1.2.2.1.8. ltInterface Nrgt
• 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 11

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• QUESTIONS