“All that is required is the ingenuity . . .”
—daemon9, coauthor of Loki1
1. daemon9, “Project Loki,” Phrack Magazine, no. 49 (1996), http://www.phrack.org/issues.html?issue=49&id=6#article.
Network tunnels are methods of encapsulating traffic in different types of protocols. Although the concept of tunneling sounds sneaky, network tunnels are often used for legitimate purposes, such as aggregating network traffic across switched virtual circuits. In certain circumstances, network tunnels are used to provide a layer of encryption for data in transit. Tunnels can also be used for illegitimate purposes, in order to hide content in ways that firewalls and NIDSs are not instrumented to detect or prevent.
In this chapter, ...