The tutorial explains how to test STP BPDU Guard feature on a cisco switch. STP BPDU Guard is a feature which is available on a Cisco switch to prevent STP based attacks. This feature is typically configured on a switch port , to which hosts are connected, and where STP packets are not required. On receipt of STP packets on the port, the port would automatically be disabled. For testing the feature , STP packet crafter can be used for the purpose. Yersinia or Scapy are useful tools which can be used for generating custom STP Packets.