Chapter 9. Transparent Firewalls

Traditionally, network firewalls have been deployed to filter traffic passing through them. These firewalls usually examine the upper-layer headers (Layer 3 or above) and occasionally the data payload in the packets. The packets are then either allowed or dropped based on the configured access control lists (ACLs). These firewalls, commonly referred as routed firewalls, segregate protected networks from unprotected ones by acting as an extra hop in the network design. They route packets from one IP subnet ...

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