Configuring and Monitoring Port Security

Reading Intrusion Alerts and Resetting Alert Flags

(by resetting the alert flag). The other entries give you a history of past intrusions detected on port A1.

Figure 9-8. Example of Multiple Intrusion Log Entries for the Same Port

The log shows the most recent intrusion at the top of the listing. You cannot delete Intrusion Log entries (unless you reset the switch to its factory-default configuration). Instead, if the log is filled when the switch detects a new intrusion, the oldest entry is dropped off the listing and the newest entry appears at the top of the listing.

 

Keeping the Intrusion Log Current by Resetting Alert

 

Flags

 

When a violation occurs on a port, an alert flag is set for that port and the

 

violation is entered in the Intrusion Log. The switch can detect and handle

 

subsequent intrusions on that port, but will not log another intrusion on the

 

port until you reset the alert flag for either all ports or for the individual port.

 

 

Note on

On a given port, if the intrusion action is to send an SNMP trap and then disable

Send-Disable

the port (send-disable), and then an intruder is detected on the port, the switch

Operation

sends an SNMP trap, sets the port’s alert flag, and disables the port. If you re-

 

enable the port without resetting the port’s alert flag, then the port operates

 

as follows:

 

■ The port comes up and will block traffic from unauthorized devices

 

it detects.

 

■ If the port detects another intruder, it will send another SNMP trap,

 

but will not become disabled again unless you first reset the port’s

 

intrusion flag.

 

This operation enables the port to continue passing traffic for authorized

 

devices while you locate and eliminate the intruder. Otherwise, the presence

 

of an intruder could cause the switch to repeatedly disable the port.

 

 

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