Configuring and Monitoring Port Security

MAC Lockdown

The key points for this Model Topology are:

• The Core Network is separated from the edge by the use of switches which have been “locked down” for security.

• All switches connected to the edge (outside users) each have only one port they can use to connect to the Core Network and then to Server A.

• Each switch has been configured with MAC Lockdown so that the MAC Address for Server A has been locked down to one port per switch that can connect to the Core and Server A.

 

Using this setup Server A can be moved around within the core network, and

 

yet MAC Lockdown will still prevent a user at the edge from hijacking its

 

address and stealing data.

 

Please note that in this scenario a user with bad intentions at the edge can still

 

“spoof” the address for Server A and send out data packets that look as though

 

they came from Server A. The good news is that because MAC Lockdown has

 

been used on the switches on the edge, any traffic that is sent back to Server

 

A will be sent to the proper MAC Address because MAC Lockdown has been

 

used. The switches at the edge will not send Server A’s data packets anywhere

 

but the port connected to Server A. (Data would not be allowed to go beyond

 

the edge switches.)

 

 

C a u t i o n

Using MAC Lockdown still does not protect against a hijacker within the core!

 

In order to protect against someone spoofing the MAC Address for Server A

 

inside the Core Network, you would have to lock down each and every switch

 

inside the Core Network as well, not just on the edge.

 

Problems Using MAC Lockdown in Networks With Multiple Paths. Now

 

 

let’s take a look at a network topology in which the use of MAC Lockdown

 

presents a problem. In the next figure, Switch 1 (on the bottom-left) is located

 

at the edge of the network where there is a mixed audience that might contain

 

hackers or other malicious users. Switch 1 has two paths it could use to

 

connect to Server A. If you try to use MAC Lockdown here to make sure that

 

all data to Server A is “locked down” to one path, connectivity problems would

 

be the result since both paths need to be usable in case one of them fails.

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