BYPASSING NETWORK ACCESS CONTROL SYSTEMS

The ease or difficulty of packet snooping (also known as eavesdropping) on networks depends largely on the technology implemented. Shared media networks are particularly susceptible to eavesdropping because this type of network transmits packets everywhere along the network as they travel from the origin to the final destination. When concentrators or hubs are used in a shared media environment (such as FDDI, 10BASE-T, or 100-Mbps Ethernet), it can be fairly easy to insert a new node with packet-capturing capability and then snoop the traffic on the network. As shown in Figure 5-2, an intruder can tap into an Ethernet switch...