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CCNA - Topics






Port Security





Port security is a layer two traffic control feature on Cisco switches. If it is enabled an administrator configure individual switch ports to allow only a specified number of source MAC addresses in the port. Configuring the Port Security feature is relatively easy. In its simplest form, port security requires going to an already enabled switch port and entering the port-security Interface Mode command

Techiebird-Sw# config ter

Techiebird-Sw(config)# int fa0/13

Techiebird-Sw(config-if)# switchport port-security ?

Aging Port-security aging commands
Mac-address Secure Mac address
Maximum Max secure addresses
Violation Security violation mode

Techiebird-Sw (config-if)# switchport port-security



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.

You can also configure port security on a range of ports.

Techiebird-Sw# config ter

Techiebird-Sw(config)# int range fastEth 0/1 – 8

Techiebird-Sw(config-if)# switchport port-security

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.

Status of port security

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.

Techiebird-Sw# show port-security address

Disabling Port Security

To disable port security we have configured fa0/13 for port security now if you want to disable port security follow the below steps.

Techiebird-Sw# config ter

Techiebird-Sw(config-if)# no switchport port-security

Techiebird-Sw(config-if)# end

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