Automatic testing of TCP/IP implementations using QuickCheck

We describe how to use model based testing for testing a network stack. We present a framework that together with the property based testing tool QuickCheck can be used to test the TCP layer of the Internet protocol stack. TCP is a rather difficult protocol to test, since it hides a lot of operations for the user that communicates to the stack via a socket interface. Internally, a lot happens and by only controlling the interface, full testing is not possible. This is typical for more complex protocols and we therefore claim that the presented method can easily be extended to other cases. We present an automatic test case generator for TCP using Quickcheck. This tester generates packet flows to test specific features of a TCP stack. It then controls the stack under test to run the test by using the interface provided by it (for example, the socket interface), and by sending replies to the packets created by the stack under test. We validated the test framework on the standard Linux TCP/IP implementation.