check_snmp_cisco_wlc – Check the avaibility of Cisco WLC Access Points

Project Notes

check_snmp_cisco_wlc is a Nagios plugin to monitor the status of
Cisco Wireless Lan Controller (former Airespace) access points

Author:
=======

Martin Fuerstenau, Oce Printing Systems GmbH, martin.fuerstenau_at_oce.com

History and Changes:
====================

- 13 Dec 2017 Version 1.5
- Added the amount of APs to output.

- 18 Apr 2016 Version 1.4
- Added --showerror_only. This will only show WLCs causing trouble.

- 21 Aug 2014 Version 1.3
- Bugfix for blacklisted items. The blacklisted AP was still written to the AP list because it was still in the hash storing all elements. Now it is deleted from the hash instead of skipped only.

- 26 Jun 2014 Version 1.2
- Fixed some small issues in help und usage.
- Added blacklist support (-B|--blacklist) for AP names. The blacklist
is a case sensitive comma seperated list. If used with --isregexp
every item of the list is interpreted as regular expression.
- 04 Dec 2013 Version 1.1 Thanks to Mihail Karageorgiev.
- Added SNMPv3 support.
- fixed last 3 bytes AP.
- 10 Aug 2012 Version 1
- First released version.

Syntax:
=======

./check_snmp_cisco_wlc -H <hostaddress> -C <community-string>

General:
========

Cisco Wireless Lan Controller (WLC) is in some parts a little bit tricky to
monitor. At present this plugin is focussed on the availability of the access
points (AP).

The plugin test for the status of an AP. If an AP is downloading it is not available. This will give a warning alert.
If it is disassociated it will give a critical alert.

If an new AP joins the WLC is automatically added with a default name (ap_name.MAC-address).
the plugin will determine this and give a warning. This warning disappears if the AP is
configured and has a "real" name.

The main problem in monitoring AP is the get an alert in case of a breakdown or power off of
an AP. This is not a monitorable alert (normally) because the AP simply disappears from the WLC
and after a power on it is back. There is no "offline" status to monitor. One method to solve this
is to handle over the number of APs. The other more flexible method is to compare it with
historical data. Therefore we will have a file to cache to old results (variable $plugin_cache around line 88).

In my case to speed up cached results the cache directory is a tmpfs.

The plugin compares the old data with the actual data. If there is no old data (first check) the actual data is stored
and will be used as old data the next run.

If old data is a subset of actual data old data is overwritten with the actual data.

If there are APs in the old data but not in the actual data an critical alert is caused.

To reset the alarm the cached data (old) can be removed by hand (but I am too lazy for this), by calling the plugin with
option -r whith host address and without community string (does the same) or it can be resetted via a trick by
acknowdging the problem.

Here is how it goes.

1. Command definition
=====================

define command{
command_name check_cisco_wlc
command_line /usr/lib/nagios/my_plugins/check_snmp_cisco_wlc -H $HOSTADDRESS$ -C $ARG1$ --showerror
}

2. Service check definition
===========================

define service{
active_checks_enabled 1
passive_checks_enabled 1
parallelize_check 1
obsess_over_service 1
check_freshness 0
notifications_enabled 1
event_handler_enabled 1
flap_detection_enabled 1
process_perf_data 1
retain_status_information 1
retain_nonstatus_information 1

host_name cisco-wlc
service_description AccessPoints
is_volatile 0
check_period 24x7
max_check_attempts 5
normal_check_interval 5
retry_check_interval 2
contact_groups network-adm,wlc-recover
notification_interval 1440
notification_period 24x7
notification_options c,w,r
check_command check_cisco_wlc!public
}

contactgroup wlc-recover is important. A direct contact is also possible-

3. contactgroup wlc-recover
===========================

This contactgroup only contains one member:

define contactgroup{
contactgroup_name wlc-recover
alias Removes WLC historic data
members wlc-recover
}

4. contact wlc-recover
======================

Look at the service_notification_commands. From service_notification_options we only need
option r but unfortunately sending a notification on for recovery is not possible.

define contact{
contact_name wlc-recover
alias wlc-recover
service_notification_period 24x7
host_notification_period 24x7
service_notification_options c,w,r
host_notification_options n
service_notification_commands recover-cisco-wlc
host_notification_commands host-notify-by-email
email [email protected]
}

5. Definition of recover-cisco-wlc
==================================

This definition call a wrapper shell script becaus we must filter out notifications for all other
than r:

define command{
command_name recover-cisco-wlc
command_line /usr/lib/nagios/my_plugins/wlc-recover "$NOTIFICATIONTYPE$" "$HOSTADDRESS$"
}

6. The little wrapper script
============================

#!/bin/bash

NOTIFICATIONTYPE=$1
HOSTADDRESS=$2

if [ "$NOTIFICATIONTYPE" = "RECOVERY" ]
then
/usr/lib/nagios/my_plugins/check_snmp_cisco_wlc -H $HOSTADDRESS -r
fi

With this trick a member of the contactgroup network-adm can acknowledge the problem (which means "Yeah - I kicked out
the AP. It's ok") and reset it to green.