Security Patterns in Practice: Designing Secure Architectures Using Software Patterns

CHAPTER 10

Security Patterns for Networks

Thus, what is of supreme importance in war is to attack the enemy’s strategy.

Sun Tzu

As network administrator I can take down the network with one keystroke. It’s just like being a doctor but without getting gooky stuff on my paws.

Scott Adams (‘Dogbert’)

10.1 Introduction

The Internet protocol suite, also referred to as TCP/IP, defines a reference model for networks that includes four layers [Sta03]: Application, Transport, Internet and Link. One can apply security to any of these layers, where two secure protocols are commonly used:

The IPSec protocol, which provides cryptographic functions at the Internet (IP) layer [For04b] [Sta06].

The Transport Layer Security (TLS) protocol, which provides similar functions at the transport (TCP) layer [For04b] [Sta06]. This protocol is based on the Secure Sockets Layer (SSL) protocol.

Figure 10.1 shows the layers and the security protocols used in each of the layers. The Application layer has different protocols based on the type of application. The Transport layer uses TLS as the security protocol, while the IP layer uses IPSec as the security protocol. Application protocols such as HTTP, LDAP and SOAP need to use the lower layers to support typical application tasks such as displaying web pages ...