a2/1cases.tex

   1 \subsection{Preflight checklist}
   2 Before actual certification is commenced we perform a manual test using a
   3 checklist.
   4 If any of the checks fail we immediately reject the product.
   5 The checklist is given in the table below. All commands in \texttt{monospace}
   6 are to be run in a terminal. Commands prefixed with a \texttt{\#} should be run
   7 with root permissions. Commands prefixed with a \texttt{\$} should be run with
   8 user permissions.
   9
  10 \begin{longtable}{|l|rp{.8\linewidth}|}
  11         \hline
  12         Check 1 & \multicolumn{2}{l|}{Get the SUT in a workable state.}\\
  13         \hline
  14         \multirow{3}{*}{Course of action}
  15                 & 1. & Import the VirtualBox image into VirtualBox.\\
  16                 & 2. & Boot the vm.\\
  17                 & 3. & Verify the SUT booted successfully and the network modules are
  18                 loaded.\\
  19         \hline
  20         Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
  21         \hline\hline
  22         Check 2 & \multicolumn{2}{l|}{Verify the SUT is complete.}\\
  23         \hline
  24         \multirow{5}{*}{Course of action}
  25                 & 1. & Boot the SUT as in \emph{Check 1}.\\
  26                 & 2. & Verify the loopback device exists by running
  27                          \texttt{\$ ifconfig}.\\
  28                 & 3. & Verify the \emph{echo-server} is present on the system by running
  29                         \texttt{\$ file code/server/Main.java}\\
  30                 & 4. & Verify \emph{Scapy} is present on the system by running
  31                         \texttt{\$ scapy}.\\
  32                 & 5. & Verify all scripts used for testing are present on the system.\\
  33         \hline
  34         Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
  35         \hline\hline
  36         Check 3 & \multicolumn{2}{l|}{Initialize the testing environment..}\\
  37         \hline
  38         \multirow{5}{*}{Course of action}
  39                 & 1. & Boot the SUT as in \emph{Check 1}.\\
  40                 & 2. & Setup iptables by executing
  41                         \texttt{\# code/iptables.sh}~\footnote{The IPTables script ensures
  42                         that the OS does not drop packets due to an the unknown source.}\\
  43                 & 3. & Navigate to the working directory by running
  44                         \texttt{\$ cd /home/student/tt2015}\\
  45                 & 4. & Compile the echo server by running
  46                         \texttt{\# cd code/server \&\& make \&\& cd -}\\
  47                 & 5. & Start the echo server by running
  48                         \texttt{\# cd code/server \&\& java Main}\\
  49         \hline
  50         Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
  51         \hline\hline
  52         Check 4 & \multicolumn{2}{l|}{Test the tool environment.}\\
  53         \hline
  54         \multirow{3}{*}{Course of action}
  55                 & 1. & Initialize the SUT as in \emph{Check 3}\\
  56                 & 2. & Execute the test script by running
  57                         \texttt{\# code/client/helloworld.py}\\
  58                 & 3. & Verify the console displays a success message.\\
  59         \hline
  60         Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
  61         \hline\hline
  62         Check 5 & \multicolumn{2}{l|}{All test inputs and scripts are present.}\\
  63         \hline
  64         \multirow{2}{*}{Course of action}
  65                 & 1. & Boot the SUT as in \emph{Check 1}.\\
  66                 & 2. & Verify that the test generation script is present by running
  67                         \texttt{\$ file code/client/test.py}\\
  68         \hline
  69         Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
  70         \hline
  71         \caption{Preflight checklist\label{tbl:preflight}}
  72 \end{longtable}
  73
  74 \subsection{Testing of SUT}
  75 The SUT is a series of services for other computer programs with no end-user
  76 facing interface. Therefore the SUT will be tested solely by calling it's
  77 services through various automated scripts. An automated test suite will be
  78 available which executes all these automated scripts and aggregates their
  79 results to asses whether or not the SUT has passed the test.
  80
  81 The implementation of the SUT is tested using black box testing techniques. A
  82 series of tests asses the correctness of the implementation with regards to the
  83 TCP specification. These tests are specified in Table~\textbf{referentie naar
  84 tests-tabel}. The test cases aim to cover the most interesting parts of the TCP
  85 specification.
  86
  87 To cover the TCP specification as complete as possible while still maintaining
  88 a feasible test suite the tests are divided into equivalence partitions. Below
  89 these partitions are given.
  90
  91 \begin{enumerate}
  92         \item \emph{Number of segments} in request~\footnote{A request is
  93                 considered establishing a connection (handshake) and a number of
  94                 payload segments}
  95                 \begin{enumerate}
  96                         \item 0 payload segments
  97                         \item 1 payload segments
  98                         \item n=small payload segments
  99                         \item n=big payload segments
 100                 \end{enumerate}
 101         \item \emph{source port}
 102                 \begin{enumerate}
 103                         \item Correct
 104                         \item Incorrect
 105                 \end{enumerate}
 106         \item \emph{destination port}
 107                 \begin{enumerate}
 108                         \item Correct
 109                         \item Incorrect
 110                 \end{enumerate}
 111         \item Bit errors in \emph{payload}
 112                 \begin{enumerate}
 113                         \item Correct payload
 114                         \item Payload with bit flips that do not show in checksum
 115                         \item Payload with bit flips that do show in checksum
 116                 \end{enumerate}
 117         \item \emph{checksum}
 118                 \begin{enumerate}
 119                         \item Correct
 120                         \item Incorrect
 121                 \end{enumerate}
 122         \item Packet order
 123                 \begin{enumerate}
 124                         \item Correct
 125                         \item Out of order
 126                         \item Missing packets
 127                 \end{enumerate}
 128 \end{enumerate}
 129
 130 These partitions were chosen since they correspond to key parts of the TCP
 131 specification.
 132
 133 TCP segments are send over a TCP connection from a \emph{source} to a \emph{destination port}. Therefore segments which are received that have a
 134 source or destination port set to an incorrect value should not be regarded
 135 as segments belonging to the connection by the SUT.
 136
 137 TCP uses a \emph{checksum} to catch any error introduced in headers, when this
 138 checksum does not match the actual computed checksum the SUT should
 139 disregard the received segment.
 140
 141 The TCP checksum is also an inherently weak one, as it is simply the
 142 bitwise negation of the addition, in ones complement arithmetic,
 143 of all 16 bit words in the header and data of the segment (excluding the
 144 checksum itself). Therefore any \emph{bit error} where the ones complement value
 145 of one word
 146 increases by one, and the value of another decreases by one, is undetected.
 147 The SUT should exhibit the same behavior and accept packets where these type
 148 of bit errors occur.
 149
 150 TCP guarantees that segments are delivered in order,even when they are received
 151 \emph{out of order} and that missing segments are resend. The SUT should
 152 exhibit the same behavior. If segments are received out of order it should
 153 deliver them in order. Missing segments should be re-requested (by ACK-ing
 154 the correct sequence number).
 155
 156 \bigskip
 157
 158 Partitions 2 to 6 are tested using pairwise testing to keep the number of test
 159 cases feasible. The pairs are then all *except some where it does not make sense
 160 to do so) tested with the different request sizes of partition 1.
 161
 162 This is expressed in Table~\ref{table:testpairs}.
 163
 164 \begin{table}[H]
 165         \centering
 166         \begin{tabular}{|l|l|l|l|l|l|l|l|l|l|l|}
 167                 \hline
 168                 & \multicolumn{10}{c|}{\textbf{Partition}}\\
 169                 \hline
 170                 & \# & 4 & 5 & 3 & 6 & 2 & 1a & 1b & 1c & 1d\\
 171                 \hline\hline
 172                 \multirow{9}{*}{Instance}
 173                 & 1 & a & a & a & a & a & \checkmark & \checkmark & \checkmark & \checkmark\\
 174                 & 2 & a & b & b & c & b & \xmark & \xmark & \checkmark & \checkmark\\
 175                 & 3 & c & a & b & a & b & \xmark & \xmark & \checkmark & \checkmark\\
 176                 & 4 & c & b & a & c & a & \xmark & \xmark & \checkmark & \checkmark\\
 177                 & 5 & b & a & b & c & a & \xmark & \xmark & \checkmark & \checkmark\\
 178                 & 6 & b & b & a & b & b & \xmark & \xmark & \checkmark & \checkmark\\
 179                 & 7 & c & b & b & a & b & \checkmark & \checkmark & \checkmark & \checkmark\\
 180                 & 8 & b & b & b & a & b & \checkmark & \checkmark & \checkmark & \checkmark\\
 181                 & 9 & a & b & b & b & a & \xmark & \xmark & \checkmark & \checkmark\\
 182                 \hline
 183 \end{tabular}
 184 \caption{Combinations of test cases}
 185 \label{table:testpairs}
 186 \end{table}
 187
 188 \subsection{Quality, completeness and coverage of tests}
 189
 190 The network packets used in testing are constructed from prerecorded, known to
 191 be correct, network traffic. These packets are then modified with well used and
 192 field tested tools. Due to this the chance of errors in the test cases is quite
 193 low. However, no formal proof of correctness of the test cases is present, this
 194 means that any defects found might not be the result of a fault in the SUT.
 195 Therefore detected defects should only indicate there is a high chance that
 196 there is a fault in the SUT and can not result directly in the conclusion that
 197 there actually is one.
 198
 199 \bigskip
 200
 201 Due to the nature of black-box testing coverage of the code in the
 202 implementation of the SUT is unknown. However completeness of the tests over
 203 the specification of the SUT can be assessed.
 204
 205 \bigskip
 206
 207 Due to the clear and exhaustive specification of TCP the completeness of the
 208 test suite can be clearly assessed.
 209
 210 As always, $100\%$ completeness is not feasible, therefore test cases are
 211 carefully selected to cover the most interesting parts of the TCP specification
 212 to ensure a test suite.
 213
 214 To further decrease the number of tests needed test cases are divided into
 215 equivalence partitions and the combination of cases as described in
 216 Table~\ref{table:testpairs} ensures that all partitions are
 217 covered and the number of individual tests is still feasible.
 218
 219
 220 %
 221 % wat ik ook probeer ik krijg de eerste collum
 222 % zijn tekst niet verticaal gecentered
 223 %
 224
 225
 226 \subsection{Test cases}
 227
 228 %\begin{table}
 229 %\begin{tabularx}{\linewidth}{| l | X|}
 230 %\hline
 231 %Nr & 1 \\\hline
 232 %Title & Single valid request. \\\hline
 233 %Input & Pcap file with prerecorded valid packets. \\\hline
 234 %Expected output & Pcap file with valid response to request. \\\hline
 235 %Course of action & \begin{enumerate}
 236 %       \item Execute \emph{./scripts/tests/case1-single-valid.sh}
 237 %       \item Load \emph{output/case1.pcap} with ...
 238 %\end{enumerate} \\\hline
 239 %Valid trace & \begin{enumerate}
 240 %       \item \textbf{Hier packets benoemen?}
 241 %\end{enumerate} \\\hline
 242 %\end{tabularx}
 243 %
 244 %\begin{tabularx}{\linewidth}{| l | X|}
 245 %       \hline
 246 %       Nr & 2 \\\hline
 247 %Title & Single request with corrupted checksum. \\\hline
 248 %       Input & Pcap file used as \emph{test-case 1} input. \\\hline
 249 %       Expected output & No response from SUT, logs with rejected packets. \\\hline
 250 %       Course of action & \begin{enumerate}
 251 %               \item Load input pcap file into ....
 252 %               \item Corrupt checksum of loaded packets.
 253 %               \item Save resulting packets as pcap file.
 254 %               \item Load new pcap file into ...
 255 %               \item Replay new pcap file.
 256 %               \item Record SUT response using...
 257 %               \item Extract log with rejected packets.
 258 %               \item Save recorded packets as a pcap file.
 259 %               \item Analyze packets in resulting file.
 260 %       \end{enumerate} \\\hline
 261 %       Valid trace & \begin{enumerate}
 262 %               \item \textbf{Aangeven welke packets corrupted zijn?}
 263 %       \end{enumerate} \\\hline
 264 %\end{tabularx}
 265 %\end{table}