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use
check_command
active_checks_enabled
passive_checks_enabled
}
define servicedependency{
name
host_name
dependent_host_name
dependent_service_description
service_description
execution_failure_criteria
}
10.4.2 Basic Nagios Plug-Ins
Plug-ins are compiled executables or scripts that can be scheduled to run on the console server to check the status of a connected host or service.
This status is then communicated to the upstream Nagios server that uses the results to monitor the current status of the distributed network. Each
console server is preconfigured with a selection of the checks that are part of the Nagios plug-ins package:
check_tcp and check_udp are used to check open ports on network hosts
check_ping is used to check network host availability
check_nrpe is used to execute arbitrary plug-ins in other devices
Each console server is preconfigured with two checks that are specific to Black Box:
check_serial_signals is used to monitor the handshaking lines on the serial ports
check_port_log is used to monitor the data logged for a serial port.
10.4.3 Number of Supported Devices
Ultimately the number of devices any particular console server can support depends upon the number of checks made, and how often they are
performed. Access method will also play a part. The table below shows the performance of three of the console servers:
Time
NSCA for single check
NSCA for 100 sequential checks
NSCA for 10 sequential checks, batched upload
NSCA for 100 sequential checks, batched upload
NRPE time to service 1 check
NRPE time to service 10 simultaneous
checks
Maximum number of simultaneous checks
before timeouts
The results were from running tests 5 times in succession with no timeouts on any runs. There are a number of ways to increase the number of
checks you can do.
Usually when using NRPE checks, an individual request will need to set up and tear down an SSL connection. This overhead can be avoided by
setting up an SSH session to the console server and tunneling the NRPE port. This allows the NRPE daemon to run securely without SSL encryption,
because SSH will provide the security.
When the console server submits NSCA results, it staggers them over a certain time period (for example, 20 checks over 10 minutes will result in
two check results every minute). Staggering the results like this means that if the power fails or other incident causes multiple problems, the
individual freshness checks will be staggered too.
NSCA checks are also batched. In the previous example, the two checks per minute are sent through in a single transaction.
generic-service
check_conn_via_Black Box!tcp!22
0
1
Black Box_nrpe_daemon_dep
Black Box
server
SSH Port
NRPE Daemon
w,u,c
No encryption
th
1/10
1 second
30
724-746-5500 | blackbox.com
Chapter 10: Nagios Integration
No encryption
3DES
~ ½ second
~ ½ second
100 seconds
100 seconds
1 ½ seconds
2 seconds
7 seconds
11 seconds
SSL
rd
second
1/3
second
3 seconds
20 (1,2 and 8) or 25
(16 and 48 port)
SSH tunnel
~ ½ second
100 seconds
1 second
6 seconds
no encryption -
tunneled over existing
SSH session
th
1/8
second
1 ¼ seconds
25 (8 port), 35 (16 and
48 port)
103
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