Hack the Route Start free Open app Switches and VLANs
Port security
A limit on how many MAC addresses one switch port accepts; one more is a violation that drops the frame or shuts the port.
With port security a port learns up to a set number of secure MAC addresses (often one: the desk's PC) and
takes no frames from any other source. A frame from one address too many is a violation, handled by the configured
mode: shutdown (the default) puts the port in the err-disabled state, down until an administrator brings it back
(shutdown / no shutdown on Cisco, or errdisable recovery after a timer); restrict drops and logs;
protect drops silently. Sticky addresses are written into the configuration as they are learned, so they survive
a restart, and a new device on that port is refused until the old address is cleared. It stops MAC flooding, a second
device plugged in behind a desk, and DHCP starvation from forged MAC addresses.