What Are The Features Of Port Security And How Does It Works?

Basically, port security is used to protect our LAN interface from the attacker. The attacker may be anyone in the organization or outside.

• You can allow mac addresses manually
• You can change or allow the maximum number of the mac address.
• If you do not configure manually, in that condition switch will allow the first source mac address 

That enters the interface.

• You can use a combination of manually configured mac addresses and as well as dynamically learned add is possible.

 How Does Port Security Works?

First whenever you enable port security on an interface with the default configuration, that time

Only one mac address is allowed. If any other mac address learns on that interface, then the port goes to the err-disable state.

There are three types of Methods of port security

1. Static Method
2. Dynamic Method
3. Sticky Method

• Static method– if we talk about the static method. we can add or remove the mac entry from the mac address-table by manually.

• Dynamic method – secondly, we will talk about the dynamic method as it can be learned One mac (1-1024) address defaults automatically.

• Stick method –it is the same as the dynamic method, but one difference is you can set the learning limit of the mac address. Another rule of it is first come first receive.

Violation Mode Of Port Security

1. Shutdown
2. Restrict
3. Protect

• Shutdown Mode

        Effectively shuts down the port by placing it into an err-disabled state.

        Generates a log and SNMP message, whenever the interface is disabled.

        The violation counter is set 1 when the interface is disabled or default 0.

• Restrict Mode

       The switch will discard traffic from an unauthorized mac address.

        That interface is not going to a disabled state.

        The violation counter is incremented by 1 each and every unauthorized frame.

         It is also generating log and SNMP messages each and an unauthorized frame.

• Protect Mode

       It does not generate any time syslog or SNMP message for unauthorized traffic.

        The interface is not disabled.

        The switch discards traffic from an unauthorized Mac address

Configuration Steps

Step 1.  enable port security

    Switch(config)#interface fa0/1

    Switch (config-if) #switchport mode access

    Switch (config-if) #switchport port-security

 Step 2. define the allowed no of the max mac address.

    Switch (config-if) #switchport port-security maximum 1

 Step 3. choose the static dynamic or sticky method

       Switch (config-if) #switchport port-security mac-address sticky/H.H.H.H

 Step 4. set the violation mode

       Switch (config-if) #switchport port-security violation shutdown/Restrict/Protect

Some verification command

Switch#show port-security address

Switch#show port-security interface fa0/1

It is great! We learned about a very basic and important feature of the cisco catalyst switch.

Those are very simple steps.

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Author
Anuj Kumar
Associate Consultant