Layer 2 of the OSI model defines the data link layer. The data link layer can be a very weak link in terms of security, and the worst thing is that it can affect the upper layers by causing service disruptions or security breaches.
At Layer 2 we can find ATM, frame relay, PPP, Ethernet, Wireless LAN (802.11a/b/g), etc. Since the most popular Layer 2 protocol is Ethernet, we will discuss its security in more detail.
MAC addresses used in Ethernet, 802.11x Wireless networks, Bluetooth, FDDI, Fiber Channel, and Token Ring are unique identifiers attached to the networking equipment. MAC addresses are 48 bits long, should be unique, and are usually shown in hexadecimal format (e.g. "00-13-F7-18-A1-AC"). The first 24-bit part of a MAC address is the manufacturer code assigned by IEEE, and the second 24 bits are assigned by the manufacturer to this interface.
By convention, the MAC address FF-FF-FF-FF-FF-FF is used for broadcast.
A security issue found at Layer...