1. How to Set Port Security on a Cisco Catalyst Switch<br />If you want to ensure that only a certain device—for example, a server—is plugged into a particular switch port, you can configure the MAC address of the server as a static entry associated with the switch port.<br />Configure port security<br />Configuring the Port Security feature is relatively easy. In its simplest form, port security requires going to an already enabled Cisco catalyst switch port and entering the port-security Interface Mode command. Here’s an example:<br />Switch# config t<br />Switch(config)# int fa0/22<br />Switch(config-if)# switchport port-security ?<br />aging Port-security aging commands<br />mac-address Secure mac address<br />maximum Max secure addresses<br />violation Security violation mode<br />Switch(config-if)# switchport port-security<br />Switch(config-if)#^Z<br />By entering the most basic command to configure port security, we accepted the default settings of only allowing one MAC address, determining that MAC address from the first device that communicates on this switch port, and shutting down that switch port if another MAC address attempts to communicate via the port. But you don’t have to accept the defaults.<br />You can also configure port security on a range of ports. Here’s an example:<br />Switch)# config t<br />Switch(config)# int range fastEthernet 0/1 - 12<br />Switch(config-if)# switchport port-security<br />However, you need to be very careful with this option if you enter this command on an uplink port that goes to more than one device. As soon as the second device sends a packet, the entire port will shut down.<br />View the status of port security<br />Once you’ve configured port security and the Ethernet device on that port has sent traffic, the switch will record the MAC address and secure the port using that address. To find out the status of port security on the switch.<br />Switch# show port-security address<br />Disabling Port Security in Cisco Switch<br />Now we will see an example how to disable port security in cisco security.We have configured fa0/22 for port security now if you want to disable port security follow these steps<br />Switch# config t<br />Switch(config)# int fa0/22<br />Switch(config-if)# no switchport port-security<br />Switch(config-if)# end<br />