Configuring and Monitoring Port Security

Reading Intrusion Alerts and Resetting Alert Flags

•Because the Port Status screen (figure 11-12on page 11-33)does not indicate an intrusion for port A1, the alert flag for the intru- sion on port A1 has already been reset.

•Since the switch can show only one uncleared intrusion per port, the alert flag for the older intrusion for port A3 in this example has also been previously reset.

(The intrusion log holds up to 20 intrusion records and deletes an intrusion record only when the log becomes full and a new intrusion is subsequently detected.)

Note also that the “prior to” text in the record for the earliest intrusion means that a switch reset occurred at the indicated time and that the intrusion occurred prior to the reset.

3.To acknowledge the most recent intrusion entry on port A3 and enable the switch to enter a subsequently detected intrusion on this port, type [R] (for Reset alert flags). (Note that if there are unacknowledged intrusions on two or more ports, this step resets the alert flags for all such ports.)

If you then re-display the port status screen, you will see that the Intrusion Alert entry for port A3 has changed to “No”. That is, your evidence that the Intrusion Alert flag has been acknowledged (reset) is that the Intrusion Alert column in the port status display no longer shows “Yes” for the port on which the intrusion occurred (port A3 in this example). (Because the Intrusion Log provides a history of the last 20 intrusions detected by the switch, resetting the alert flags does not change its content. Thus, displaying the Intrusion Log again will result in the same display as in figure 11-13, above.)

CLI: Checking for Intrusions, Listing Intrusion Alerts, and Resetting Alert Flags

The following commands display port status, including whether there are intrusion alerts for any port(s), list the last 20 intrusions, and either reset the alert flag on all ports or for a specific port for which an intrusion was detected. (The record of the intrusion remains in the log. For more information, refer to “Operating Notes for Port Security” on page 11-38.)

Syntax: show interfaces brief

List intrusion alert status (and other port status informa- tion)’.

show port-security intrusion-log

List intrusion log content.

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