No concept carries more importance when discussing network security than .Defense in depth helps you protect network resources even if one of the security layers is compromised.When mitigating such risks, we must consider what our organization's crown jewels are and what protecting them is worth when we implement defense in depth if we want to avoid similar problems for our organizations. The simple answer is the perimeter, the internal network, and a human factor.
If your Internet connection is relatively small (T1 or less), then performing filtering solely on a firewall might be sufficient.
Unlike static packet filtering devices, stateful firewalls keep track of connections in a state table and are the most common type of firewall.
Crown Jewels Think of any information that would have significant adverse affects if compromised as your organization's crown jewels. In response, Maxim posted 25,000 numbers on a website on Christmas Day 1999.
CD-Universe had their crown jewels compromised and undoubtedly felt the effects in lost sales and consumer confidence.
In this case, spoofing allowed attackers to direct the large number of responses to a victim network.