\documentclass[a4paper,french,12pt]{article}

\title{Networks and Protocols --- Wireshark Lab 3}
\author{Yi Yang --- Alexandre Chen --- Tunui Franken}

\usepackage{../cours}

\begin{document}

\maketitle

\section{Ethernet --- ARP}

    \subsection{Capturing and analyzing Ethernet frames}

        \begin{enumerate}

            \item \texttt{00:d0:59:a9:3d:68}.

            \item \texttt{00:06:25:da:af:73}.
                \texttt{gaia.cs.umass.edu} is not in the same network.
                The MAC address is that of the next hop router (gateway).

            \item \texttt{0x0800}.
                This corresponds to IPv4.

            \item \texttt{0x47} (71 in decimal) starts at byte 54.

            \item \texttt{00:06:25:da:af:73}.
                It is the destination address of the GET message (next hop router).

            \item \texttt{00:d0:59:a9:3d:68} (our computer).

            \item \texttt{0x0800}.
                This corresponds to IPv4.

            \item The O (\texttt{0x4f}) from the HTTP response can be found at byte 13.

        \end{enumerate}

    \subsection{The Address Resolution Protocol}

        \begin{enumerate}\setcounter{enumi}{8}

            \item First column~: IPv4 address\\
                Second column~: MAC address\\
                Third column~: Type, ie.\ how the entry was learned
                \begin{lstlisting}[gobble=20]
                    IP Address      MAC Address         Type
                    10.3.0.3        64:12:25:4a:46:c1   static
                    10.3.101.222    f8:ac:65:b5:59:28   static
                    10.3.0.2        00:1a:1e:07:9c:d0   dynamic
                    10.3.0.1        00:00:0c:07:ac:0d   static
                    10.3.0.4        f8:72:ea:ae:df:3c   static
                \end{lstlisting}

            \item src~: \texttt{00:d0:59:a9:3d:68}\\
                dst~: \texttt{ff:ff:ff:ff:ff:ff}\\

            \item \texttt{0x0806}, which corresponds to ARP\@.

            \item
                \begin{enumerate}
                    \item Opcode \texttt{request} is at byte 20.
                    \item The hexadecimal value is \texttt{OxOOO1} (1).
                    \item Yes, \texttt{192.168.1.105}, so that the sender can receive a response.
                    \item The target MAC address is set to \texttt{00:00:00:00:00:00} because it is unknown.
                \end{enumerate}

            \item
                \begin{enumerate}
                    \item Opcode \texttt{reply} is at byte 20.
                    \item The hexadecimal value is \texttt{OxOOO2} (2).
                    \item The answer appears as Sender MAC address~: \texttt{00:06:25:da:af:73}, corresponding to IPv4 address \texttt{192.168.1.1}.
                \end{enumerate}

            \item src~: \texttt{00:06:25:da:af:73}\\
                dst~: \texttt{00:d0:59:a9:3d:68}\\

            \item Maybe no host in the network has the queried IP address (\texttt{192.168.1.117}).

        \end{enumerate}

\section{ICMP}

    \subsection{ICMP and Ping}

        \begin{enumerate}

            \item src~: \texttt{192.168.1.101} \\
                dst~: \texttt{143.89.14.34}

            \item Although it resides on the Transport layer, ICMP does not use UDP nor TCP\@.
                ICMP does not use ports.

            \item Type~: 8 --- Echo (ping) request \\
                Code~: 0.

                The other fields are~: \\
                Checksum~: 2 bytes \\
                Identifier~: 2 bytes \\
                Sequence Number~: 2 bytes \\
                Data.

            \item Type~: 0 --- Echo (ping) reply \\
                Code~: 0.

                The other fields are~: \\
                Checksum~: 2 bytes \\
                Identifier~: 2 bytes \\
                Sequence Number~: 2 bytes \\
                Data.

        \end{enumerate}

    \subsection{ICMP and Traceroute}

        \begin{enumerate}\setcounter{enumi}{4}

            \item src~: \texttt{192.168.1.101} \\
                dst~: \texttt{138.96.146.2}

            \item The number for UDP protocol would be 17 (\texttt{0x11}).

            \item The echo request is the same is for the first half of this lab.

            \item The error ICMP packet has an additional \texttt{Unused} field.
                It also includes part of the Echo request that this error is for.

            \item These packets are not error messages, but normal ICMP replies (Type 0 instead of Type 11).
                The error messages had exceeded TTL values.
                This indicates that the ping made it to the destination.

            \item The delayed link seems to be NYC --- Pastourelle (n. 9 to n. 10).
                This is a link the crosses the Atlantic ocean.

        \end{enumerate}

\end{document}
