final

[tt2015.git] / a2 / 1cases.tex

\subsection{Preflight checklist}
Before actual certification is commenced we perform a manual test using a 
checklist.
If any of the checks fail we immediately reject the product.
The checklist is given in the table below. All commands in \texttt{monospace}
are to be run in a terminal. Commands prefixed with a \texttt{\#} should be run
with root permissions. Commands prefixed with a \texttt{\$} should be run with
user permissions.

\begin{longtable}{|l|rp{.8\linewidth}|}
        \hline
        Check 1 & \multicolumn{2}{l|}{Get the SUT in a workable state.}\\
        \hline
        \multirow{3}{*}{Course of action} 
                & 1. & Import the VirtualBox image into VirtualBox.\\
                & 2. & Boot the vm.\\
                & 3. & Verify the SUT booted successfully and the network modules are
                loaded.\\
        \hline
        Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
        \hline\hline
        Check 2 & \multicolumn{2}{l|}{Verify the SUT is complete.}\\
        \hline
        \multirow{5}{*}{Course of action}
                & 1. & Boot the SUT as in \emph{Check 1}.\\
                & 2. & Verify the loopback device exists by running 
                         \texttt{\$ ifconfig}.\\
                & 3. & Verify the \emph{echo-server} is present on the system by running
                        \texttt{\$ file code/server/Main.java}\\
                & 4. & Verify \emph{Scapy} is present on the system by running
                        \texttt{\$ scapy}.\\
                & 5. & Verify all scripts used for testing are present on the system.\\
        \hline
        Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
        \hline\hline
        Check 3 & \multicolumn{2}{l|}{Initialize the testing environment..}\\
        \hline
        \multirow{6}{*}{Course of action}
                & 1. & Boot the SUT as in \emph{Check 1}.\\
                & 2. & Setup iptables by executing
                        \texttt{\# code/iptables.sh}~\footnote{The IPTables script ensures
                        that the OS does not drop packets due to an the unknown source.}\\
                & 3. & Navigate to the working directory by running
                        \texttt{\$ cd /home/student/tt2015}\\
                & 4. & Compile the echo server by running 
                        \texttt{\# cd code/server \&\& make}\\
                & 5. & Start the echo server by running
                        \texttt{\# cd code/server \&\& java Main}\\
                & 6. & Generate all test cases by running
                        \texttt{\$ python code/client/gen.py}\\
        \hline
        Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
        \hline\hline
        Check 4 & \multicolumn{2}{l|}{Test the tool environment.}\\
        \hline
        \multirow{3}{*}{Course of action}
                & 1. & Initialize the SUT as in \emph{Check 3}\\
                & 2. & Execute the test script by running
                        \texttt{\# code/client/helloworld.py}\\
                & 3. & Verify the console displays a success message.\\
        \hline
        Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
        \hline\hline
        Check 5 & \multicolumn{2}{l|}{All test inputs and scripts are present.}\\
        \hline
        \multirow{2}{*}{Course of action}
                & 1. & Boot the SUT as in \emph{Check 1}.\\
                & 2. & Verify that the test generation script is present by running
                        \texttt{\$ file code/client/test.py}\\
        \hline
        Passed & \multicolumn{2}{l|}{\textit{Yes/No}}\\
        \hline
        \caption{Preflight checklist\label{tbl:preflight}}
\end{longtable}

\subsection{Testing of SUT} \label{sec:testingofsut}
The SUT is a series of services for other computer programs with no end-user
facing interface. Therefore the SUT will be tested solely by calling it's
services through various automated scripts. An automated test suite will be
available which executes all these automated scripts and aggregates their
results to asses whether or not the SUT has passed the test. 

The implementation of the SUT is tested using black box testing techniques. A
series of tests asses the correctness of the implementation with regards to the
TCP specification. These tests are specified in Table~\ref{tbl:testpairs}. The test cases aim to cover the most interesting parts of the TCP
specification. 

In this test suite the behavior of the outwards (network) interface of the SUT
is assessed. This is, the behavior of the SUT as
observed by another system on the network trying to communicate with (a system
running on the same host as the SUT using) the SUT. This is achieved by running
man 
echo-server on the system which runs the SUT (a virtual machine) which
echos back all messages received to the sender. The test scripts will send
packets to the echo-server and then checks the received
response to asses whether or not the SUT is preforming as expected.

To cover the TCP specification as complete as possible while still maintaining
a feasible test suite the tests are divided into equivalence partitions. Below
these partitions are given.

\begin{enumerate}
        \item \emph{Number of segments} in request~\footnote{A request is
                considered establishing a connection (handshake) and a number of
                payload segments}
                \begin{enumerate}
                        \item 0 payload segments
                        \item 1 payload segments
                        \item n=small payload segments (1 byte)
                        \item n=big payload segments (65495 bytes)
                \end{enumerate}
        \item \emph{source port}
                \begin{enumerate}
                        \item Correct
                        \item Incorrect
                \end{enumerate}
        \item \emph{destination port}
                \begin{enumerate}
                        \item Correct
                        \item Incorrect
                \end{enumerate}
        \item Bit errors in \emph{payload}
                \begin{enumerate}
                        \item Correct payload
                        \item Payload with bit flips that do not show in checksum
                        \item Payload with bit flips that do show in checksum
                \end{enumerate}
        \item \emph{checksum}
                \begin{enumerate}
                        \item Correct
                        \item Incorrect
                \end{enumerate}
        \item \emph{Segment order}
                \begin{enumerate}
                        \item Correct
                        \item Out of order
                        \item Missing Segments
                \end{enumerate}
\end{enumerate}

These partitions were chosen since they correspond to key parts of the TCP
specification. 

%
% één na laatste packket, moet dit B+3 of B+2 zijn?
%

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 
source or destination port set to an incorrect value should not be regarded
as segments belonging to the connection by the SUT. 

TCP uses a \emph{checksum} to catch any error introduced in headers, when this
checksum does not match the actual computed checksum the SUT should
disregard the received segment.

The TCP checksum is also an inherently weak one, as it is simply the 
bitwise negation of the addition, in ones complement arithmetic, 
of all 16 bit words in the header and data of the segment (excluding the
checksum itself). Therefore any \emph{bit error} where the ones complement value
of one word
increases by one, and the value of another decreases by one, is undetected. 
The SUT should exhibit the same behavior and accept packets where these type
of bit errors occur.

TCP guarantees that segments are delivered \emph{in order}
, even when they are received
out of order and that missing segments are resend. The SUT should
exhibit the same behavior. If segments are received out of order it should
either reassemble them when the missing segment has arrived or request them to
be resend. Missing segments should be re-requested (by ACK-ing
their sequence number).  

A single request consists of a number of segments that are sent
to the \emph{echo-server} and back. The TCP specification states that such a
transaction requires the following messages.

\begin{flushleft}
        Script $-$ SYN $A$ $\rightarrow$ SUT \\
        Script $\leftarrow$ SYN-ACK $(A+1)$ $B$ $-$ SUT \\
        Script $-$ ACK $(A+1)$ $(B+1)$ $\rightarrow$ SUT \\
        Script $-$ ACK-PUSH $(A+1)$ $(B+2)$ \emph{msg} $\rightarrow$ SUT \\
        Script $\leftarrow$ ACK $(A+2+msg_{length})$ $(B+3)$ $-$ SUT \\
        Script $\leftarrow$ ACK-PUSH $(A+2+msg_{length})$ $(B+3)$ \emph{msg} $-$ SUT
\end{flushleft}

%
% RS ook? FIN?
%

When the \emph{SUT} has received the ACK containing the message it's passed 
trough to the \emph{echo-server}. The \emph{echo-server} will proceed by ordering 
the \emph{SUT} to respond by sending the exact same message. When this happens 
the \emph{SUT} has to construct the last segment in the transaction listed above.

\bigskip

Partitions 2 to 6 are tested using pairwise testing to keep the number of test
cases feasible. The pairs are then all *except some where it does not make sense
to do so) tested with the different request sizes of partition 1.

This is expressed in Table~\ref{tbl:testpairs}. In this table the first five
columns represent the different options for the partitions 2 to 6 of the above
enumeration. The last four columns are the different number segments as
described in the partition 1 of the above enumeration. These cells identify
individual test cases by a number. An \xmark in the cell indicates that this
test case can not be created as it is not possible with that number of segments
(eg. sending segments out of order when the number of segments is 1).

\setcounter{TCC}{1}
\begin{table}[H]
        \centering
        \begin{tabular}{|l|l|l|l|l|l||l|l|l|l|}
                \hline
                & \multicolumn{9}{c|}{\textbf{Partition}}\\
                \hline
                & 4 & 5 & 3 & 6 & 2 & 1a & 1b & 1c & 1d\\
                \hline\hline
                \multirow{9}{*}{Instance} 
                & a & a & a & a & a & \doTCC & \doTCC & \doTCC & \doTCC\\
                & a & b & b & c & b & \xmark & \xmark & \doTCC & \doTCC\\
                & c & a & b & a & b & \xmark & \xmark & \doTCC & \doTCC\\
                & c & b & a & c & a & \xmark & \xmark & \doTCC & \doTCC\\
                & b & a & b & c & a & \xmark & \xmark & \xmark & \doTCC\\
                & b & b & a & b & b & \xmark & \xmark & \xmark & \doTCC\\
                & c & b & b & a & b & \xmark & \doTCC & \doTCC & \doTCC\\
                & b & b & b & a & b & \xmark & \xmark & \xmark & \doTCC\\
                & a & b & b & b & a & \xmark & \xmark & \doTCC & \doTCC\\
                \hline
        \end{tabular}
\caption{Combinations of test cases}
\label{tbl:testpairs}
\end{table}

\subsection{Quality, completeness and coverage of tests}

The network packets used in testing are constructed from prerecorded, known to
be correct, network traffic. These packets are then modified with well used and 
field tested tools. Due to this the chance of errors in the test cases is quite
low. However, no formal proof of correctness of the test cases is present, this
means that any defects found might not be the result of a fault in the SUT.
Therefore detected defects should only indicate there is a high chance that 
there is a fault in the SUT and can not result directly in the conclusion that
there actually is one. 

\bigskip

Due to the nature of black-box testing coverage of the code in the 
implementation of the SUT is unknown. However completeness of the tests over 
the specification of the SUT can be assessed. 

\bigskip

Due to the clear and exhaustive specification of TCP the completeness of the 
test suite can be clearly assessed. 

As always, $100\%$ completeness is not feasible, therefore test cases are
carefully selected to cover the most interesting parts of the TCP specification
to ensure a complete but feasible test suite.

%To further increase the coverage of the test suites tests are randomized. The
%tests which test the handling of \emph{bit errors}, changes in the \emph{segment
%order} and \emph{dropped segments} randomize where they introduce an error. The
%test suite runs these tests multiple times to increase the likelihood that they
%discover a fault which is only present when an error occurs in a certain
%position. 

To further decrease the number of tests needed test cases are divided into
equivalence partitions and the combination of cases as described in 
Table~\ref{tbl:testpairs} ensures that all partitions are
covered and the number of individual tests is still feasible. 


%
% wat ik ook probeer ik krijg de eerste collum
% zijn tekst niet verticaal gecentered
%


\subsection{Test suite}

Before executing the test suite the test environment has to be initialized. 

\begin{enumerate}
        \item Boot the vm using VirtualBox.
        \item Setup iptables by executing \texttt{\# code/iptables.sh}
        \item Navigate to the working directory by running 
                \texttt{\$ cd /home/student/tt2015}
        \item Start the echo server by running 
                \texttt{\# cd code/server \&\& Java Main}
\end{enumerate}

\subsubsection{Preflight checks}
The we do the preflight checks as defined in Table~\ref{tbl:preflight}.

\subsubsection{Test Cases}
If the SUT passes the preflight checks the actual test cases can be executed.
Table~\ref{tbl:testcases} shows the expected results of each of the test cases
described in Table~\ref{tbl:testpairs}. 

\setcounter{TCC}{1}
\begin{table}[H]
        \centering
    \begin{tabular}{|l|p{.7\linewidth}|}
        \hline
        Test number & Expected results\\  
        \hline\hline
        \doTCC & An ACK\# of the send sequence number + 1.\\  \hline
        \doTCC & An ACK\# of the sequence number of the last send segment + the
                size of the payload of that segment.\\  \hline
        \doTCC & An ACK\# of the sequence number of the last send segment + the
                size of the payload of that segment.\\  \hline
        \doTCC & An ACK\# of the sequence number of the last send segment + the
                size of the payload of that segment.\\  \hline
        \doTCC & The ACK\# for the SEQ\# of the first segments which is
                corrupted is received for each consecutive segment send.\\  
        $\vdots$ & \\  
        \setcounter{TCC}{12}
        \doTCC & The ACK\# for the SEQ\# of the first segments which is
                corrupted is received for each consecutive segment send.\\  \hline
        \doTCC & The segment is not attributed to the current connection
                and therefore no ACK\# is received. \\  \hline
        \doTCC & The ACK\# for the SEQ\# of the first segments which is
                corrupted is received for each consecutive segment send.\\  \hline
        \doTCC & The ACK\# for the SEQ\# of the first segments which is
                corrupted is received for each consecutive segment send.\\  \hline
        \doTCC & The ACK\# for the SEQ\# of the first segments which is
                corrupted is received for each consecutive segment send.\\ \hline
        \doTCC & The ACK\# for the SEQ\# of the first segments which is
                corrupted is received for each consecutive segment send.\\  \hline
        \doTCC & The ACK\# for the SEQ\# of the first segments which is
                corrupted is received for each consecutive segment send.\\ \hline
    \end{tabular}
\caption{Expected results of test cases}
\label{tbl:testcases}
\end{table}

% Bij Ramons afwezigheid
% Paul Vitero (linkerkant lange gang)
% verdieping Mercator


\begin{longtable}{|p{.2\linewidth}|p{.8\linewidth}|}
        \hline
        
        Nr & 1 \\\hline
        Title & Connect to the \emph{echo-server} without sending a payload. \\\hline
        Input & Generated packets. \\\hline
        Expected output & \emph{Echo-server} accepts the connection. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/1.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline
        
        Nr & 2 \\\hline
        Title & Single valid request with 1byte payload. \\\hline
        Input & Generated packets. \\\hline
        Expected output & Packets echoed back by Echo-Server. \\\hline
        \multirow{2}{*}{Course of action}
 & 1. Use the steps listed above in order to start the SUT. \\
 & 2. Execute the script by running \texttt{\# code/client/tests/1.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline
        
%       Nr & 3 \\\hline
%       Title & Single valid request with 65495bytes payload. \\\hline
%       Input & Generated packets. \\\hline
%       Expected output & Packets echoed back by Echo-Server. \\\hline
%       \multirow{2}{*}{Course of action}
%       & 1. Use the steps listed above in order to start the SUT. \\
%       & 2. Execute the script by running \texttt{\# code/client/tests/2.py} \\\hline
%       Valid trace & Verify that the script prints 'Success'. \\\hline
%       \hline
        
        Nr & 3 \\\hline
        Title & 5 valid requests with 1byte payload. \\\hline
        Input & Generated packets. \\\hline
        Expected output & Packets echoed back by Echo-Server, in the same order as the client sent them. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/3.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline

        Nr & 4 \\\hline
        Title & 5 valid requests with 65495bytes payload. \\\hline
        Input & Generated packets with 65495bytes payload. \\\hline
        Expected output & Packets echoed back by Echo-Server, in the same order as the client sent them. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/4.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline

        Nr & 5 \\\hline
        Title & 5 requests with 1byte payload with corrupted source port, destination port and checksum. The second segment is omitted in order to simulate a packet drop on the client side. \\\hline
        Input & Generated packets with 1byte payload, second generated segment is removed. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/5.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline

        Nr & 6 \\\hline
        Title & 5 requests with 65495byte payload with corrupted source port, destination port and checksum. The second segment is omitted in order to simulate a packet drop on the client side. \\\hline
        Input & Generated segments with 65495byte payload, second generated segment is removed. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/6.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline
        
        %% HIER
        
        Nr & 7 \\\hline
        Title & 5 requests with 1byte corrupted payload, corrupted source and destination port. \\\hline
        Input & Generated packets with 1byte payload, in these packets the payload byte, source and destination ports are increased by one. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/7.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline
        
        Nr & 8 \\\hline
        Title & 5 requests with 65495byte corrupted payload, corrupted source and destination port. \\\hline
        Input & Generated packets with 65495byte payload, in these packets one of the payload bytes, source and destination ports are increased by one. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/8.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline
        
        
        Nr & 9 \\\hline
        Title & 5 requests with 1byte corrupted payload, invalid checksum and the second packet is dropped. \\\hline
        Input & Generated packets with 1byte payload, in these packets the payload byte and checksum are increased by one. The second segment is removed. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/9.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline
        
        Nr & 10 \\\hline
        Title & 5 requests with 65495byte corrupted payload, invalid checksum and the second packet is dropped. \\\hline
        Input & Generated packets with 65495byte payload, in these packets one of the payload bytes and the checksum are increased by one. The second packet is removed. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/10.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline
        
        Nr & 11 \\\hline
        Title & 5 requests with 65495byte corrupted payload that doesn't show up in checksum and corrupted destination port. The second packet is dropped. \\\hline
        Input & Generated packets with 65495byte payload, in these packets one 16bit word in the payload is increased by 1 and another 16bit word is decreased by 1. The destination port is also increase by one and the second segment is removed. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/11.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline


        Nr & 12 \\\hline
        Title & 5 requests with 65495byte corrupted payload that doesn't show up in checksum and corrupted source port and checksum. The 2nd and 3rd packets are swapped. \\\hline
        Input & Generated packets with 65495byte payload, in these packets one 16bit word in the payload, the source port and checksum are increased by one. A different 16bit word in the payload is decreased by one. The 2nd and 3rd packets are swapped in order to simulate a out-of-order transmission. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/12.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline

        
        Nr & 13 \\\hline
        Title & Single request with 1byte corrupted payload and corrupted source port, destination port and checksum. \\\hline
        Input & Generated segment with 1byte payload, in this segment one byte in the payload, the source port and checksum are increased by one. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/13.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline

        Nr & 14 \\\hline
        Title & 5 requests with 1byte corrupted payload and corrupted source port, destination port and checksum. \\\hline
        Input & Generated packets with 1byte payload, in these segment one byte in the payload, the source port and checksum are increased by one. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/14.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline
        
        Nr & 15 \\\hline
        Title & 5 requests with 65495byte corrupted payload and corrupted source port, destination port and checksum. \\\hline
        Input & Generated packets with 65495byte payload, in these packets one byte in the payload, the source port and checksum are increased by one. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/15.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline

        Nr & 16 \\\hline
        Title & 5 requests with 65495byte corrupted payload that doesn't show up in the checksum, corrupted source port, destination port and checksum. \\\hline
        Input & Generated packets with 65495byte payload, in these packets one 16bit word in the payload, the source port and checksum are increased by one. Another 16bit word in the payload is decreased by 1. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/16.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline
        
        
        Nr & 17 \\\hline
        Title & 5 requests with 1byte payload, corrupted destination port and checksum. The 2nd and 3rd packets are swapped \\\hline
        Input & Generated packets with 1byte payload, in these packets the destination port and checksum are increased by one. The 2nd and 3rd packets are swapped in order to simulate an out-of-order transmission. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/17.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline


        Nr & 18 \\\hline
        Title & 5 requests with 65495byte payload, corrupted destination port and checksum. The 2nd and 3rd packets are swapped \\\hline
        Input & Generated packets with 65495byte payload, in these packets the destination port and checksum are increased by one. The 2nd and 3rd packets are swapped in order to simulate an out-of-order transmission. \\\hline
        Expected output & All packets are dropped resulting in a connection time-out. \\\hline
        \multirow{2}{*}{Course of action}
        & 1. Use the steps listed above in order to start the SUT. \\
        & 2. Execute the script by running \texttt{\# code/client/tests/18.py} \\\hline
        Valid trace & Verify that the script prints 'Success'. \\\hline
        \hline  
\end{longtable}

%\begin{tabularx}{\linewidth}{| l | X|}
%\hline
%Nr & 1 \\\hline
%Title & Single valid request. \\\hline
%Input & Pcap file with prerecorded valid packets. \\\hline
%Expected output & Pcap file with valid response to request. \\\hline
%Course of action & \begin{enumerate}
%       \item Execute \emph{./scripts/tests/case1-single-valid.sh}
%       \item Load \emph{output/case1.pcap} with ...
%\end{enumerate} \\\hline
%Valid trace & \begin{enumerate}
%       \item \textbf{Hier packets benoemen?}
%\end{enumerate} \\\hline
%\end{tabularx}
%
%\begin{tabularx}{\linewidth}{| l | X|}
%       \hline
%       Nr & 2 \\\hline
%Title & Single request with corrupted checksum. \\\hline
%       Input & Pcap file used as \emph{test-case 1} input. \\\hline
%       Expected output & No response from SUT, logs with rejected packets. \\\hline
%       Course of action & \begin{enumerate}
%               \item Load input pcap file into ....
%               \item Corrupt checksum of loaded packets.
%               \item Save resulting packets as pcap file.
%               \item Load new pcap file into ...
%               \item Replay new pcap file.
%               \item Record SUT response using...
%               \item Extract log with rejected packets.
%               \item Save recorded packets as a pcap file.
%               \item Analyze packets in resulting file.
%       \end{enumerate} \\\hline
%       Valid trace & \begin{enumerate}
%               \item \textbf{Aangeven welke packets corrupted zijn?}
%       \end{enumerate} \\\hline
%\end{tabularx}
%\end{table}