Chapter 9:
Nagios Integration
204
No encryption
SSL
no encryption - tunneled
over existing SSH session
NRPE time to service 1 check
1/10
th
second
1/3
rd
second
1/8
th
second
NRPE time to service 10
simultaneous checks
1 second
3 seconds
1 ¼ seconds
Maximum number of
simultaneous checks before
timeouts
30
20 (1,2 and
8) or 25 (16
and 48 port)
25 (1,2 and 8 port), 35 (16
and 48 port)
The results were from running tests 5 times in succession with no timeouts on any runs. However 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 be run securely without SSL encryption, as SSH
will take care of the security.
When the console server submits NSCA results it staggers them over a certain time period (e.g. 20 checks
over 10 minutes will result in two check results every minute). Staggering the results like this means that
in the event of a power failure or other incident that causes multiple problems, the individual freshness
checks will be staggered too.
NSCA checks are also batched, so in the previous example the two checks per minute will be sent through
in a single transaction.
9.3.5 Distributed Monitoring Usage Scenarios
Below are a number of distributed monitoring Nagios scenarios:
I.
Local office
In this scenario, the console server is set up to monitor the console of each managed device. It can be
configured to make a number of checks, either actively at the Nagios server's request, or passively at
preset intervals, and submit the results to the Nagios server in a batch.
The console server may be augmented at the local office site by one or more Intelligent Power Distribution
Units (IPDUs) to remotely control the power supply to the managed devices.
