Silence on the Wire

Chapter 7. Secure in Switched Networks

Or, why Ethernet LANs cannot be quite fixed, no matter how hard we try

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Ethernet networks do not provide a universal and easy way to ensure the integrity or confidentiality of the data they transmit, nor are they engineered to with-stand malicious, intentionally injected traffic. Ethernet is merely a means for interfacing a number of local, presumably trusted systems.

Assuming this level of trust is convenient at the design stage and is theoretically sufficient for peer systems on the same network and often at roughly the same physical location. But, as the old saying goes, only in theory is there no difference between theory and practice. In practice, there is a difference.

As it turns out, local networks are ...