Physical layer

From Computing and Software Wiki

Description: The Physical layer is responsible for encoding and transmission of data over network communications media. It operates with data in the form of bits that are sent from the Physical layer of the sending (source) device and received at the Physical layer of the destination device.

Ethernet, Token Ring, SCSI, hubs, repeaters, cables and connectors are standard network devices that function at the Physical layer. The Physical layer is also considered the domain of many hardware-related network design issues, such as LAN and WAN topology and wireless technology.

An example of an attack:

some one can physically take away your network card or unplug your internet cable.

A way to defense:

Don't let people touch your computer :) it gets more complicated with wireless technologies