1intro.tex

   1 \subsection{Objectives}
   2 %1, 2
   3 The objective of this document is to provide an approach for testing a
   4 particular implementation of \textit{Transmission Control Protocol} (TCP). TCP
   5 is a host-to-host protocol that provides a reliable communication.
   6
   7 This testing approach can be used by either an internal test team or an
   8 independent testing team. The test effort's goal is to become confident about
   9 the conformance of an existing implementation to the specification created by
  10 \textit{The Internet Engineering Task Force}
  11 (IETF)\footnote{\url{http://www.ietf.org}} as document
  12 \textit{RFC793}~\cite{rfc793}. This document is explicitly \emph{not} intended
  13 to serve as guideline for testing during the development phase, but for testing
  14 conformity to the specification of an \emph{existing} implementation.
  15
  16 \subsection{SUT}
  17 %3,4
  18 The \textit{System under test} (SUT) is a
  19 Java\footnote{\url{http://www.java.com}} TCP driven echo server that executed
  20 on a virtualized Ubuntu system\footnote{\url{http://www.ubuntu.com}} running on
  21 the Linux kernel\footnote{\url{http://www.kernel.org}} version $3.13$. To test
  22 the error behaviour custom iptables output policies have to be set
  23 Listing~\ref{listing:iptables}. This is needed because the kernel by default
  24 closes all connections from unknown sources and the manually created TCP
  25 packets used in testing the implementation are from a source unknown to the
  26 kernel.
  27
  28 \begin{lstlisting}[label={listing:iptables},caption={settings iptables}]
  29 Chain OUTPUT (policy ACCEPT)
  30 target  prot    opt     source  destination
  31 ACCEPT  tcp     --      anywhere        anywhere        tcp flags:PSH/PSH
  32 DROP    tcp     --      anywhere        anywhere        tcp flags:RST/RST
  33 \end{lstlisting}
  34
  35 \subsection{Risks} \label{sec:risks}
  36 %5. Risks
  37 Risks can be divided into two categories. Project risks and product risks.
  38 Because an existing implementation is used the project risk are non applicable.
  39 Product risks even more so, since it is unknown if the product has been tested
  40 during development.
  41
  42 The product risks for the SUT are significant because misbehaviour of the SUT
  43 could have potential large consequences. The key characteristics of TCP are
  44 integrity and reliability~\cite{rfc793}, these characteristics cease to exist
  45 when the implementation is faulty.
  46
  47 Because TCP is a core functionality of a networking capable system it is
  48 crucial that the TCP implementation functions according to the specification.
  49 Several critical systems could rely on the correct functionality of the TCP
  50 implementation. A failure in the SUT could therefore have extensive
  51 consequences. Even more so since TCP is a computer-to-computer protocol, which
  52 leaves no room for ambiguity, which could be solved in a computer-to-human
  53 protocol.