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{6}{*}{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}\\
  47                 & 5. & Start the echo server by running
  48                         \texttt{\# cd code/server \&\& java Main}\\
  49                 & 6. & Generate all test cases by running
  50                         \texttt{\$ python code/client/gen.py}\\
  51         \hline
  52         Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
  53         \hline\hline
  54         Check 4 & \multicolumn{2}{l|}{Test the tool environment.}\\
  55         \hline
  56         \multirow{3}{*}{Course of action}
  57                 & 1. & Initialize the SUT as in \emph{Check 3}\\
  58                 & 2. & Execute the test script by running
  59                         \texttt{\# code/client/helloworld.py}\\
  60                 & 3. & Verify the console displays a success message.\\
  61         \hline
  62         Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
  63         \hline\hline
  64         Check 5 & \multicolumn{2}{l|}{All test inputs and scripts are present.}\\
  65         \hline
  66         \multirow{2}{*}{Course of action}
  67                 & 1. & Boot the SUT as in \emph{Check 1}.\\
  68                 & 2. & Verify that the test generation script is present by running
  69                         \texttt{\$ file code/client/test.py}\\
  70         \hline
  71         Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
  72         \hline
  73         \caption{Preflight checklist\label{tbl:preflight}}
  74 \end{longtable}
  75
  76 \subsection{Testing of SUT}
  77 The SUT is a series of services for other computer programs with no end-user
  78 facing interface. Therefore the SUT will be tested solely by calling it's
  79 services through various automated scripts. An automated test suite will be
  80 available which executes all these automated scripts and aggregates their
  81 results to asses whether or not the SUT has passed the test.
  82
  83 The implementation of the SUT is tested using black box testing techniques. A
  84 series of tests asses the correctness of the implementation with regards to the
  85 TCP specification. These tests are specified in Table~\ref{tbl:testpairs}. The test cases aim to cover the most interesting parts of the TCP
  86 specification.
  87
  88 To cover the TCP specification as complete as possible while still maintaining
  89 a feasible test suite the tests are divided into equivalence partitions. Below
  90 these partitions are given.
  91
  92 \begin{enumerate}
  93         \item \emph{Number of segments} in request~\footnote{A request is
  94                 considered establishing a connection (handshake) and a number of
  95                 payload segments}
  96                 \begin{enumerate}
  97                         \item 0 payload segments
  98                         \item 1 payload segments
  99                         \item n=small payload segments (1 byte)
 100                         \item n=big payload segments (65495 bytes)
 101                 \end{enumerate}
 102         \item \emph{source port}
 103                 \begin{enumerate}
 104                         \item Correct
 105                         \item Incorrect
 106                 \end{enumerate}
 107         \item \emph{destination port}
 108                 \begin{enumerate}
 109                         \item Correct
 110                         \item Incorrect
 111                 \end{enumerate}
 112         \item Bit errors in \emph{payload}
 113                 \begin{enumerate}
 114                         \item Correct payload
 115                         \item Payload with bit flips that do not show in checksum
 116                         \item Payload with bit flips that do show in checksum
 117                 \end{enumerate}
 118         \item \emph{checksum}
 119                 \begin{enumerate}
 120                         \item Correct
 121                         \item Incorrect
 122                 \end{enumerate}
 123         \item \emph{Segment order}
 124                 \begin{enumerate}
 125                         \item Correct
 126                         \item Out of order
 127                         \item Missing Segments
 128                 \end{enumerate}
 129 \end{enumerate}
 130
 131 These partitions were chosen since they correspond to key parts of the TCP
 132 specification. A single request consists of a number of packets that sent a
 133 to the \emph{echo-server} and back. The TCP specification state that such a
 134 transaction requires the following messages.
 135
 136 \begin{center}
 137         Script $-$ SYN $A$ $\rightarrow$ SUT \\
 138         Script $\leftarrow$ SYN-ACK $(A+1)$ $B$ $-$ SUT \\
 139         Script $-$ ACK $(A+1)$ $(B+1)$ $\rightarrow$ SUT \\
 140         Script $-$ ACK-PUSH $(A+1)$ $(B+2)$ \emph{msg} $\rightarrow$ SUT \\
 141         Script $\leftarrow$ ACK $(A+2+msg_{length})$ $(B+3)$ $-$ SUT \\
 142         Script $\leftarrow$ ACK-PUSH $(A+2+msg_{length})$ $(B+3)$ \emph{msg} $-$ SUT
 143 \end{center}
 144
 145 %
 146 % één na laatste packket, moet dit B+3 of B+2 zijn?
 147 %
 148
 149 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
 150 source or destination port set to an incorrect value should not be regarded
 151 as segments belonging to the connection by the SUT.
 152
 153 TCP uses a \emph{checksum} to catch any error introduced in headers, when this
 154 checksum does not match the actual computed checksum the SUT should
 155 disregard the received segment.
 156
 157 The TCP checksum is also an inherently weak one, as it is simply the
 158 bitwise negation of the addition, in ones complement arithmetic,
 159 of all 16 bit words in the header and data of the segment (excluding the
 160 checksum itself). Therefore any \emph{bit error} where the ones complement value
 161 of one word
 162 increases by one, and the value of another decreases by one, is undetected.
 163 The SUT should exhibit the same behavior and accept packets where these type
 164 of bit errors occur.
 165
 166 TCP guarantees that segments are delivered \emph{in order}
 167 ,even when they are received
 168 out of order and that missing segments are resend. The SUT should
 169 exhibit the same behavior. If segments are received out of order it should
 170 either reassemble them when the missing packet has arrived or request them to
 171 be resend when the  Missing segments should be re-requested (by ACK-ing
 172 the correct sequence number).
 173
 174 \bigskip
 175
 176 Partitions 2 to 6 are tested using pairwise testing to keep the number of test
 177 cases feasible. The pairs are then all *except some where it does not make sense
 178 to do so) tested with the different request sizes of partition 1.
 179
 180 This is expressed in Table~\ref{tbl:testpairs}. In this table the first five
 181 columns represent the different options for the partitions 2 to 6 of the above
 182 enumeration. The last four columns are the different number segments as
 183 described in the partition 1 of the above enumeration. These cells identify
 184 individual test cases by a number. An \xmark in the cell indicates that this
 185 test case can not be created as it is not possible with that number of segments
 186 (eg. sending segments out of order when the number of segments is 1).
 187
 188 \setcounter{TCC}{1}
 189 \begin{table}[H]
 190         \centering
 191         \begin{tabular}{|l|l|l|l|l|l||l|l|l|l|}
 192                 \hline
 193                 & \multicolumn{9}{c|}{\textbf{Partition}}\\
 194                 \hline
 195                 & 4 & 5 & 3 & 6 & 2 & 1a & 1b & 1c & 1d\\
 196                 \hline\hline
 197                 \multirow{9}{*}{Instance}
 198                 & a & a & a & a & a & \doTCC & \doTCC & \doTCC & \doTCC\\
 199                 & a & b & b & c & b & \xmark & \xmark & \doTCC & \doTCC\\
 200                 & c & a & b & a & b & \xmark & \xmark & \doTCC & \doTCC\\
 201                 & c & b & a & c & a & \xmark & \xmark & \doTCC & \doTCC\\
 202                 & b & a & b & c & a & \xmark & \xmark & \doTCC & \doTCC\\
 203                 & b & b & a & b & b & \xmark & \xmark & \doTCC & \doTCC\\
 204                 & c & b & b & a & b & \xmark & \doTCC & \doTCC & \doTCC\\
 205                 & b & b & b & a & b & \xmark & \doTCC & \doTCC & \doTCC\\
 206                 & a & b & b & b & a & \xmark & \xmark & \doTCC & \doTCC\\
 207                 \hline
 208         \end{tabular}
 209 \caption{Combinations of test cases}
 210 \label{tbl:testpairs}
 211 \end{table}
 212
 213 \subsection{Quality, completeness and coverage of tests}
 214
 215 The network packets used in testing are constructed from prerecorded, known to
 216 be correct, network traffic. These packets are then modified with well used and
 217 field tested tools. Due to this the chance of errors in the test cases is quite
 218 low. However, no formal proof of correctness of the test cases is present, this
 219 means that any defects found might not be the result of a fault in the SUT.
 220 Therefore detected defects should only indicate there is a high chance that
 221 there is a fault in the SUT and can not result directly in the conclusion that
 222 there actually is one.
 223
 224 \bigskip
 225
 226 Due to the nature of black-box testing coverage of the code in the
 227 implementation of the SUT is unknown. However completeness of the tests over
 228 the specification of the SUT can be assessed.
 229
 230 \bigskip
 231
 232 Due to the clear and exhaustive specification of TCP the completeness of the
 233 test suite can be clearly assessed.
 234
 235 As always, $100\%$ completeness is not feasible, therefore test cases are
 236 carefully selected to cover the most interesting parts of the TCP specification
 237 to ensure a complete but feasible test suite.
 238
 239 To further increase the coverage of the test suites tests are randomized. The
 240 tests which test the handling of \emph{bit errors}, changes in the \emph{packet
 241 order} and \emph{dropped packets} randomize where they introduce an error. The
 242 test suite runs these tests multiple times to increase the likelihood that they
 243 discover a fault which is only present when an error occurs in a certain
 244 position.
 245
 246 To further decrease the number of tests needed test cases are divided into
 247 equivalence partitions and the combination of cases as described in
 248 Table~\ref{tbl:testpairs} ensures that all partitions are
 249 covered and the number of individual tests is still feasible.
 250
 251
 252 %
 253 % wat ik ook probeer ik krijg de eerste collum
 254 % zijn tekst niet verticaal gecentered
 255 %
 256
 257
 258 \subsection{Test suite}
 259
 260 Before executing the test suite the test environment has to be initialized.
 261
 262 \begin{enumerate}
 263         \item Boot the vm using VirtualBox.
 264         \item Setup iptables by executing \texttt{\# code/iptables.sh}
 265         \item Navigate to the working directory by running
 266                 \texttt{\$ cd /home/student/tt2015}
 267         \item Start the echo server by running
 268                 \texttt{\# cd code/server \&\& Java Main}
 269 \end{enumerate}
 270
 271 \subsubsection{Preflight checks}
 272 The we do the preflight checks as defined in Table~\ref{tbl:preflight}.
 273
 274 \subsubsection{Test Cases}
 275 If the SUT passes the preflight checks the actual test cases can be executed.
 276 Table~\ref{tbl:testcases} shows the expected results of each of the test cases
 277 described in Table~\ref{tbl:testpairs}.
 278
 279 \setcounter{TCC}{1}
 280 \begin{table}[H]
 281         \centering
 282     \begin{tabular}{|l|p{.7\linewidth}|}
 283         \hline
 284         Test number & Expected results\\
 285         \hline\hline
 286         \doTCC & An ACK\# of the send sequence number + 1.\\  \hline
 287         \doTCC & An ACK\# of the sequence number of the last send segment + the
 288                 size of the payload of that segment.\\  \hline
 289         \doTCC & An ACK\# of the sequence number of the last send segment + the
 290                 size of the payload of that segment.\\  \hline
 291         \doTCC & An ACK\# of the sequence number of the last send segment + the
 292                 size of the payload of that segment.\\  \hline
 293         \doTCC & The ACK\# for the SEQ\# of the first segments which is
 294                 corrupted is received for each consecutive segment send.\\
 295         $\vdots$ & \\
 296         \setcounter{TCC}{14}
 297         \doTCC & The ACK\# for the SEQ\# of the first segments which is
 298                 corrupted is received for each consecutive segment send.\\  \hline
 299         \doTCC & The segment is not attributed to the current connection
 300                 and therefore no ACK\# is received. \\  \hline
 301         \doTCC & The ACK\# for the SEQ\# of the first segments which is
 302                 corrupted is received for each consecutive segment send.\\  \hline
 303         \doTCC & The ACK\# for the SEQ\# of the first segments which is
 304                 corrupted is received for each consecutive segment send.\\  \hline
 305         \doTCC & The segment is not attributed to the current connection
 306                 and therefore no ACK\# is received. \\  \hline
 307         \doTCC & The ACK\# for the SEQ\# of the first segments which is
 308                 corrupted is received for each consecutive segment send.\\  \hline
 309         \doTCC & The ACK\# for the SEQ\# of the first segments which is
 310                 corrupted is received for each consecutive segment send.\\ \hline
 311         \doTCC & The ACK\# for the SEQ\# of the first segments which is
 312                 corrupted is received for each consecutive segment send.\\  \hline
 313         \doTCC & The ACK\# for the SEQ\# of the first segments which is
 314                 corrupted is received for each consecutive segment send.\\ \hline
 315     \end{tabular}
 316 \caption{Expected results of test cases}
 317 \label{tbl:testcases}
 318 \end{table}
 319
 320 % Bij Ramons afwezigheid
 321 % Paul Vitero (linkerkant lange gang)
 322 % verdieping Mercator
 323
 324
 325 %\begin{longtable}{|p{.2\linewidth}|p{.8\linewidth}|}
 326         %\hline
 327         %Nr & 1 \\\hline
 328         %Title & Single valid request with 1byte payload. \\\hline
 329         %Input & Generated packets. \\\hline
 330         %Expected output & Packets echoed back by Echo-Server. \\\hline
 331         %\multirow{2}{*}{Course of action}
 332  %& 1. Use the steps listed above in order to start the SUT. \\
 333  %& 2. Execute the script by running \texttt{\# code/client/tests/1.py} \\\hline
 334         %Valid trace & Verify that the script prints 'Success'. \\\hline
 335         %\hline
 336 %
 337         %Nr & 2 \\\hline
 338         %Title & Single valid request with 65495bytes payload. \\\hline
 339         %Input & Generated packets. \\\hline
 340         %Expected output & Packets echoed back by Echo-Server. \\\hline
 341         %\multirow{2}{*}{Course of action}
 342         %& 1. Use the steps listed above in order to start the SUT. \\
 343         %& 2. Execute the script by running \texttt{\# code/client/tests/2.py} \\\hline
 344         %Valid trace & Verify that the script prints 'Success'. \\\hline
 345         %\hline
 346 %
 347         %Nr & 3 \\\hline
 348         %Title & 5 valid requests with 1byte payload. \\\hline
 349         %Input & Generated packets. \\\hline
 350         %Expected output & Packets echoed back by Echo-Server, in the same order as the client sent them. \\\hline
 351         %\multirow{2}{*}{Course of action}
 352         %& 1. Use the steps listed above in order to start the SUT. \\
 353         %& 2. Execute the script by running \texttt{\# code/client/tests/3.py} \\\hline
 354         %Valid trace & Verify that the script prints 'Success'. \\\hline
 355         %\hline
 356 %
 357         %Nr & 4 \\\hline
 358         %Title & 5 valid requests with 65495bytes payload. \\\hline
 359         %Input & Generated packets with 65495bytes payload. \\\hline
 360         %Expected output & Packets echoed back by Echo-Server, in the same order as the client sent them. \\\hline
 361         %\multirow{2}{*}{Course of action}
 362         %& 1. Use the steps listed above in order to start the SUT. \\
 363         %& 2. Execute the script by running \texttt{\# code/client/tests/4.py} \\\hline
 364         %Valid trace & Verify that the script prints 'Success'. \\\hline
 365         %\hline
 366 %
 367         %Nr & 5 \\\hline
 368         %Title & 5 valid requests with 1byte payload sent out of order. \\\hline
 369         %Input & Generated packets with 1byte payload, two packets are swapped in position. \\\hline
 370         %Expected output & All requests sent up to and including
 371          %the swapped packet with the lowest sequence number, the remaining packets are dropped. \\\hline
 372         %\multirow{2}{*}{Course of action}
 373         %& 1. Use the steps listed above in order to start the SUT. \\
 374         %& 2. Execute the script by running \texttt{\# code/client/tests/5.py} \\\hline
 375         %Valid trace & Verify that the script prints 'Success'. \\\hline
 376         %\hline
 377 %
 378         %Nr & 6 \\\hline
 379         %Title & Request with corrupted source port. \\\hline
 380         %Input & Generated packets with 1byte payload, in these packets the source port number is increased by one. \\\hline
 381         %Expected output & - \\\hline
 382         %\multirow{2}{*}{Course of action}
 383         %& 1. Use the steps listed above in order to start the SUT. \\
 384         %& 2. Execute the script by running \texttt{\# code/client/tests/6.py} \\\hline
 385         %Valid trace & Verify that the script prints 'Success'. \\\hline
 386         %\hline
 387 %
 388 %
 389         %Nr & 6 \\\hline
 390         %Title & Request with corrupted destination port. \\\hline
 391         %Input & Generated packets with 1byte payload, in these packets the destination port number is increased by one. \\\hline
 392         %Expected output & - \\\hline
 393         %\multirow{2}{*}{Course of action}
 394         %& 1. Use the steps listed above in order to start the SUT. \\
 395         %& 2. Execute the script by running \texttt{\# code/client/tests/6.py} \\\hline
 396         %Valid trace & Verify that the script prints 'Success'. \\\hline
 397         %\hline
 398 %
 399 %\end{longtable}
 400
 401 %\begin{tabularx}{\linewidth}{| l | X|}
 402 %\hline
 403 %Nr & 1 \\\hline
 404 %Title & Single valid request. \\\hline
 405 %Input & Pcap file with prerecorded valid packets. \\\hline
 406 %Expected output & Pcap file with valid response to request. \\\hline
 407 %Course of action & \begin{enumerate}
 408 %       \item Execute \emph{./scripts/tests/case1-single-valid.sh}
 409 %       \item Load \emph{output/case1.pcap} with ...
 410 %\end{enumerate} \\\hline
 411 %Valid trace & \begin{enumerate}
 412 %       \item \textbf{Hier packets benoemen?}
 413 %\end{enumerate} \\\hline
 414 %\end{tabularx}
 415 %
 416 %\begin{tabularx}{\linewidth}{| l | X|}
 417 %       \hline
 418 %       Nr & 2 \\\hline
 419 %Title & Single request with corrupted checksum. \\\hline
 420 %       Input & Pcap file used as \emph{test-case 1} input. \\\hline
 421 %       Expected output & No response from SUT, logs with rejected packets. \\\hline
 422 %       Course of action & \begin{enumerate}
 423 %               \item Load input pcap file into ....
 424 %               \item Corrupt checksum of loaded packets.
 425 %               \item Save resulting packets as pcap file.
 426 %               \item Load new pcap file into ...
 427 %               \item Replay new pcap file.
 428 %               \item Record SUT response using...
 429 %               \item Extract log with rejected packets.
 430 %               \item Save recorded packets as a pcap file.
 431 %               \item Analyze packets in resulting file.
 432 %       \end{enumerate} \\\hline
 433 %       Valid trace & \begin{enumerate}
 434 %               \item \textbf{Aangeven welke packets corrupted zijn?}
 435 %       \end{enumerate} \\\hline
 436 %\end{tabularx}
 437 %\end{table}