Monitoring; Real-Time Monitor Alerts; The Link Monitor - D-Link NetDefendOS User Manual

2.4. Monitoring

The real-time performance of NetDefendOS can be monitored in a number of ways. They are:
• NetDefendOS real-time monitor alerts.
• The NetDefendOS link monitor.
• Monitoring through an SNMP client.
• Hardware monitoring for specific hardware models.

2.4.1. Real-time Monitor Alerts

A number of NetDefendOS statistical values can graphically monitored through the Real-time
Monitoring feature. Real-time Monitor Alert thresholds can be specified in NetDefendOS for any of
these monitored values so that they can have a maximum and/or a minimum numerical
threshold.
Should a specified maximum or minimum threshold be crossed, NetDefendOS will automatically
generate a log message which will be sent to all configured log receivers. All such log messages
belong to the REALTIMEMONITOR message category which has the identity number 54.
The log message identity will therefore take the form 054XXXXX where XXXXX represents the
position of the statistic generating the event in the list of alert rules. A log message with identity
05400003, for example, identifies the third rule in the rule list.
Monitor Alert Rules
Each Monitor Alert Rule consists of the following fields:
Name
Sample time
Low threshold
High threshold
Continuous
Backoff

2.4.2. The Link Monitor

Overview
The Link Monitor is a NetDefendOS feature that allows monitoring of the connectivity to one or
more IP addresses external to the NetDefend Firewall. This monitoring is done using standard
User assigned name for the rule.
The interval in seconds between checking the statistic.
The lower threshold (if specified).
A higher threshold (if specified).
This determines if an event is also generated when the threshold is
crossed in the other direction. In other words, the statistic moves back to
within acceptable limits. This field can be Yes or No.
The minimum number of seconds between consecutive Monitor Threshold
Rule log messages. This value can be useful in preventing a flood of log
messages when a statistic is repeatedly passing a threshold and then
receding from it again.
103
Chapter 2: Management and Maintenance