What does switchport port-security protect command do?

The switchport port-security protect command is used in Cisco switches to enable port security on a specific switch port. When this command is configured, the port will allow traffic only from MAC addresses that are already learned and stored in the port's memory. If an unauthorized MAC address tries to connect, the switch will drop the traffic from that address, effectively preventing unauthorized access while allowing legitimate traffic through. This security measure helps to mitigate risks associated with MAC flooding and unauthorized devices.