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Chapter 10: Nagios Integration
10.2 Central management and setting up SDT for Nagios 
The Nagios solution has three parts: the Central Nagios server, Distributed Console Servers and the SDT for Nagios software.
 
Central Nagios server
• A vanilla Nagios 2.x or 3.x installation (typically on a Linux server)\
• Generally running on a blade, PC, virtual machine, etc. at a central loc\
ation
• Runs a web server that displays the Nagios GUI
• Imports configuration from distributed Console Servers 
Distributed Console Servers 
• B096-016 / B096-032 / B096-048 or B092-016 Console Servers
• Serial and network hosts are attached to each Console Server
• Each runs Nagios plug-ins, NRPE and NSCA add-ons, but not a full Nagios \
server
Clients
• Typically a client PC, laptop, etc. running Windows, Linux or Mac OS X
• Runs Tripp Lite SDT Connector client software 1.5.0 or later
• Connect to the central Nagios server web UI to view status of monitored \
hosts and serial devices
• Then use SDT Connector to connect through the distributed Console Server\
s, to manage monitored hosts and serial 
devices
10.2.1  Set up central Nagios server
The Nagios server software is available for most major distributors of L\
inux using the standard package management tools. 
Your distributor will have documentation available on how to install Nagi\
os. This is usually the quickest and simplest way to get 
up and running.
Note that you will need the core Nagios server package, and at least one\
 of the NRPE or NSCA add-ons. NSCA is required to 
utilize the alerting features of the distributed hosts; installing both \
NRPE and NSCA is recommended.
You will also require a web server such as Apache to display the Nagios w\
eb UI (and this may be installed automatically as a 
dependency of the Nagios packages).
Alternatively, you may wish to download the Nagios source code directly from the Nagi\
os website, and build and install the 
software from scratch. The Nagios website (http://www.nagios.org) has several Quick Start Guides that walk through this 
process.
Once you are able to browse to your Nagios server and see its web UI and\
 the local services it monitors by default, you are 
ready to continue.  
						

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10.2.2 Set up distributed Console Servers 
This section provides a brief walk-through on configuring a single Con\
sole Server to monitor the status of one attached network 
host (a Windows IIS server running HTTP and HTTPS services) and one serially attached device (the console port of a \
network 
router), and to send alerts back to the Nagios server when an administr\
ator connects to the router or IIS server. 
While this walk-through provides an example, details of the configurat\
ion options are described in the next section. This walk-
through also assumes the network host and serial devices are already phy\
sically connected to the Console Server. First step is 
to set up the Nagios features on the Console Server:
• Browse the Console Server and select System: Nagios on the Console Server Management Console. Check Nagios 
service Enabled
• Enter the Host Name and the Nagios Host Address (i.e. IP address) that the central Nagios server will use to contact \
the distributed Console Server 
• Enter the IP address that the distributed Console Server will use to con\
tact the central Nagios server in Nagios Server 
Address
• Enter the IP address that the clients running SDT Connector will use to \
connect through the distributed Console Servers in 
SDT Gateway address
• Check Prefer NRPE, NRPE Enabled and NRPE Command Arguments
• Check NSCA Enabled, choose an NSCA Encryption Method and enter and confirm an NSCA Secret. Remember these 
details as you will need them later on. For NSCA Interval, enter 5
• Click Apply.
Next, configure the attached Window network host and specify the services you will be checking with Na\
gios (HTTP and 
HTTPS):
• Select Network Hosts from the Serial & Network menu and click Add Host.
• Enter the IP Address/DNS Name of the network server, (e.g.: 192.168.1.10) and enter a Description, (e.g.: Windows 
2003 IIS Server)
• Remove all Permitted Services. This server will be accessible using Terminal Services, so check TCP, Port 3389 and log 
level 1 and click Add. It is important to remove and re-add the service to enable logging  
						

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Chapter 10: Nagios Integration
• Scroll down to Nagios Settings and check Enable Nagios
• Click New Check and select Check Ping. Click check-host-alive 
• Click New Check and select Check Permitted TCP. Select Port 3389
• Click New Check and select Check TCP. Select Port 80
• Click New Check and select Check TCP. Select Port 443
• Click Apply
Similarly, configure the serial port to the router to be monitored by Nagios:
• Select Serial Port from the Serial & Network menu
• Locate the serial port that has the router console port attached and cli\
ck Edit
• Ensure the serial port settings under Common Settings are correct and match the attached router’s console port
• Click Console Server Mode and select Logging Level 1
• Check Telnet (SSH access is not required, as SDT Connector is used to secure the otherw\
ise unsecured Telnet connection)
•  Scroll down to Nagios Settings and check Enable Nagios
• Check Port Log and Serial Status
• Click Apply
Now set the Console Server to send alerts to the Nagios server 
• Select Alerts from the Alerts & Logging menu and click Add Alert 
• In Description enter: Administrator connection
• Check Nagios (NSCA)
• In Applicable Ports check the serial port that has the router console port attached. In Applicable Hosts check the IP 
address/DNS name of the IIS server
• Click Connection Alert
• Click Apply
Lastly, add a User for the client running SDT Connector:
• Select Users & Groups from the Serial & Network menu
• Click Add User
• In Username, enter: sdtnagiosuser, then enter and confirm a Password
• In Accessible Hosts click the IP address/DNS name of the IIS server. In Accessible Ports click the serial port that has 
the router console port attached
• Click Apply  
						

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10.3 Configuring Nagios distributed monitoring
To activate the Console Server’s Nagios distributed monitoring:
• Nagios integration must be enabled and a path established to the central\
/upstream Nagios server
• If the Console Server is to periodically report on Nagios-monitored serv\
ices, then the NSCA client embedded in the 
Console Server must be configured: the NSCA program enables scheduled \
check-ins with the remote Nagios server and is 
used to send passive check results across the network to the remote serv\
er 
• If the Nagios server is to actively request status updates from the Cons\
ole Server, then the NRPE server embedded in the 
Console Server must be configured – the NRPE server is the Nagios d\
aemon for executing plug-ins on remote hosts
• Each of the Serial Ports and each of the Hosts connected to the Console Server which are to \
be monitored must have 
Nagios enabled and any specific Nagios checks configured
• Lastly the central/upstream Nagios monitoring host must be configured \
10.3.1  Enable Nagios on the Console Server
• Select System: Nagios on the Console Server Management Console and tick the Nagios service Enabled
 
• Enter the Nagios Host Name that the Console Server will be referred to in the Nagios central serve\
r – this will be 
generated from local System Name (entered in System: Administration) if unspecified
• In Nagios Host Address, enter the IP address or DNS name that the upstream Nagios server will \
use to reach the 
Console Server – if unspecified this will default to the first ne\
twork port’s IP as entered in System: IP)
• In Nagios Server Address, enter the IP address or DNS name that the Console Server will use to r\
each the upstream 
Nagios monitoring server
• Check the Disable SDT Nagios Extensions option if you wish to disable the SDT Connector integration with your N\
agios 
server at the head end – this would only be checked if you want to ru\
n a vanilla Nagios monitoring
• If not, enter the IP address or DNS name the SDT Nagios clients will use\
 to reach the Console Server in SDT Gateway 
Address
• When NRPE and NSCA are both enabled, NSCA is preferred method for commun\
icating with the upstream Nagios server – 
check Prefer NRPE to use NRPE whenever possible (i.e. for all communication except for a\
lerts)  
						

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Chapter 10: Nagios Integration
10.3.2  Enable NRPE monitoring 
 
Enabling NRPE allows you to execute plug-ins (such as check_tcp and check_ping) on the remote Console Server to monitor 
serial or network attached remote servers. This will offload CPU load \
from the upstream Nagios monitoring machine which is 
especially valuable if you are monitoring hundreds or thousands of hosts\
. To enable NRPE:
• Select System: Nagios and check NRPE Enabled
• Enter the details for the user connection to the upstream Nagios monitor\
ing server. Again, refer to the sample Nagios 
configuration example below for details of configuring specific NR\
PE checks 
By default, the Console Server will accept a connection between the upst\
ream Nagios monitoring server and the NRPE server 
with SSL encryption, without SSL, or tunneled through SSH. The security for the connection is configured at the Nagios server\
.   
						

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10.3.3  Enable NSCA monitoring 
NSCA is the mechanism that allows you to send passive check results from\
 the remote Console Server to the Nagios daemon 
running on the monitoring server. To enable NSCA:
• Select System: Nagios and check NSCA Enabled
• Select the Encryption to be used from the drop-down menu, then enter a Secret password and specify a check Interval
• Refer the sample Nagios configuration section below for some examples \
of configuring specific NSCA checks   
						

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Chapter 10: Nagios Integration
10.3.4 Configure selected Serial Ports for Nagios monitoring
The individual Serial Ports connected to the Console Server to be monitored must be configure\
d for Nagios checks. Refer to 
Chapter 4.4: Network Host Configuration for details on enabling Nagios monitoring for Hosts that are network co\
nnected to the 
Console Server. To enable Nagios to monitor a device connected to the Console Server seri\
al port:
• Select Serial & Network: Serial Port and click Edit on the serial Port # to be monitored
• Select Enable Nagios, specify the name of the device on the upstream server and determine th\
e check to be run on this 
port. Serial Status monitors the handshaking lines on the serial port and Check Port monitors the data logged for the 
serial port
10.3.5 Configure selected Network Hosts for Nagios monitoring
The individual Network Hosts connected to the Console Server that is to \
be monitored must also be configured for Nagios 
checks:
• Select Serial & Network: Network Port and click Edit on the Network Host to be monitored
• Select Enable Nagios, specify the name of the device as it will appear on the upstream Nagio\
s server 
• Click New Check to add a specific check which will be run on this host
• Select Check Permitted TCP/UDP to monitor a service that you have previously added as a Permitted Service
• Select Check TCP/UDP to specify a service port that you wish to monitor, but do not wish to allow external (SDT 
Connector) access
• Select Check TCP to monitor  
						

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Chapter 10: Nagios Integration
• The Nagios Check nominated as the check-host-alive check is used to determine whether the network host itself is up 
or down
• Typically this will be Check Ping – although in some cases the host will be configured not to respon\
d to pings
• If no check-host-alive check is selected, the host will always be assumed to be up
• You may deselect check-host-alive by clicking Clear check-host-alive
• If required, customize the selected Nagios Checks to use custom arguments
• Click Apply
10.3.6  Configure the upstream Nagios monitoring host
Refer to the Nagios documentation (http://www.nagios.org/docs/) for configuring the upstream server:
• The section entitled Distributed Monitoring steps through what is needed to configure NSCA on the upstream server\
 (under 
Central Server Configuration)
• NRPE Documentation, which has been recently added, steps through configuring NRPE on the\
 upstream server http://
nagios.sourceforge.net/docs/nrpe/NRPE.pdf
At this stage, Nagios at the upstream monitoring server is configured,\
 and individual serial port and network host connections 
on the Console Server are configured for Nagios monitoring. If NSCA is\
 enabled, each selected check will be executed once 
over the period of the check interval. If NRPE is enabled, then the upst\
ream server will be able to request status updates 
under its own scheduling.  
						

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Chapter 10: Nagios Integration
10.4 Advanced Distributed Monitoring Configuration
10.4.1  Sample Nagios configuration 
An example configuration for Nagios is listed below. It shows how to set up a remote Console Server to monitor a single hos\
t, 
with both network and serial connections. Each check has two configura\
tions, one for NRPE and one for NSCA. In practice, 
these would be combined into a single check which uses NSCA as a primary\
 method and falling back to NRPE if a check were 
late. For details, see the Nagios documentation (http://www.nagios.org/docs/) on Service and Host Freshness Checks.
; Host definitions
;
; Console Server
define host{
        use                     generic-host
        host_name               tripplite
        alias                   Console Server
        address                 192.168.254.147
        }
; Managed Host
define host{
        use                     generic-host
        host_name               server 
        alias                   server
        address                 192.168.254.227
        }
; NRPE daemon on gateway
define command {
 command_name check_nrpe_daemon
 command_line  $USER1$/check_nrpe -H 192.168.254.147 -p 5666
 }
define service {
 service_description  NRPE Daemon
 host_name  tripplite
 use   generic-service
 check_command  check_nrpe_daemon
 }
; Serial Status
define command {
 command_name check_serial_status
 command_line  $USER1$/check_nrpe -H 192.168.254.147 -p 5666 -c check_serial_$HOSTNAME$\
 }
define service {
 service_description  Serial Status
 host_name  server
 use   generic-service
 check_command  check_serial_status
 }  
						

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Chapter 10: Nagios Integration
define service {
 service_description serial-signals-server
 host_name  server
 use   generic-service
 check_command  check_serial_status
 active_checks_enabled 0
 passive_checks_enabled 1
 }
define servicedependency{
 name    tripplite_nrpe_daemon_dep
 host_name   tripplite
 dependent_host_name  server
 dependent_service_description  Serial Status
 service_description  NRPE Daemon
 execution_failure_criteria w,u,c
 }
; Port Log
define command{
 command_name    check_port_log
 command_line    $USER1$/check_nrpe -H 192.168.254.147 -p 5666 -c port_lo\
g_$HOSTNAME$
        }
define service {
 service_description  Port Log
 host_name  server
 use   generic-service
 check_command  check_port_log
 }
define service {
 service_description port-log-server
 host_name  server
 use   generic-service
 check_command  check_port_log
 active_checks_enabled 0
 passive_checks_enabled 1
 }
define servicedependency{
 name    tripplite_nrpe_daemon_dep
 host_name   tripplite
 dependent_host_name  server
 dependent_service_description  Port Log
 service_description  NRPE Daemon
 execution_failure_criteria w,u,c
 }
; Ping
define command{
 command_name    check_ping_via_tripplite
 command_line    $USER1$/check_nrpe -H 192.168.254.147 -p 5666 -c host_pi\
ng_$HOSTNAME$
        }