Common Application Design Considerations
This chapter covers the following topics:
- DNS
- HTTP/HTTPS
- FTP
- Instant Messaging
- Application Evaluation
I don't want to insist on it, Dave, but I am incapable of making an error.
Arthur C. Clarke, 2001: A Space Odyssey, 1968
The Answer to the Great Question . . . Of Life, the Universe and Everything . . . Is . . . Forty-two.
Douglas Adams, The Hitch Hiker's Guide to the Galaxy, 1979
Although this book will certainly not go into great detail on application security, in certain cases application security relies on the network for its overall security strategy. This chapter presents best practices for the deployment of e-mail, DNS, HTTP/HTTPS, and FTP. A short discussion on instant messaging (IM) and application security evaluations is also provided. The emphasis in this chapter is on network placement and filtering guidelines, not application hardening. In addition to these placement guidelines, be sure to follow the hardening steps in Chapter 5, "Device Hardening," and deploy host security controls as discussed in Chapter 4, "Network Security Technologies." Specific application security recommendations for these protocols can be found online or in any number of books, some of which are referenced in this chapter.
NOTE
The examples used in this chapter are focused on the firewall. The deployment of intrusion detection systems (IDS) and other security technologies is expected but not included because such technologies don't generally impact the logical topology of the network. Similar designs with all security components included (and multiple applications) are included in Part 3 of this book.