Marks$)$

Given below a Point$-$to$-$point communication trace taken by Wireshark a network protocol analyzer software.

ETHER: $-----$ Ether Header $-----$

ETHER:

ETHER: Packet $11$ arrived at $17$:$37$:$32\mathrm{.}18$

ETHER: Packet size $=54$ bytes

ETHER: Destination $=0$:e$0$:f$7$:$26$:$3$f:e$9$

ETHER: Source $=8$:$0$:$20$:$86$:$35$:$4$b

ETHER: Ethertype $=0800($IP$)$

ETHER:

IP: $-----$ IP Header $-----$

IP:

IP: Version $=4$

IP: Header length $=20$ bytes

IP: Type of service $=0$x$00$

IP: xxx$.....=0($precedence$)$

IP: $..\mathrm{.}0....=$ normal delay

IP: $....0...=$ normal throughput

IP: $....\mathrm{.}0..=$ normal reliability

IP: Total length $=40$ bytes

IP: Identification $=2236$

IP: Flags $=0$x$4$

IP: $\mathrm{.}1......=$ do not fragment

IP: $.\mathrm{.}0.....=$ last fragment

IP: Fragment offset $=0$ bytes

IP: Time to live $=64$

IP: Protocol $=6$

IP: Header checksum $=9997$

IP: Source address $=139\mathrm{.}133\mathrm{.}217\mathrm{.}110$

IP: Destination address $=139\mathrm{.}133\mathrm{.}233\mathrm{.}2$

IP: No options

IP:

TCP: $-----$ TCP Header $-----$

TCP:

TCP: Source port $=36869$

TCP: Destination port $=23($TELNET$)$

TCP: Sequence number $=1913975089$

TCP: Acknowledgement number $=0$

TCP: Data offset $=20$ bytes

TCP: Flags $=0$x$02$

TCP: $.\mathrm{.}0.....=$ urgent pointer

TCP: $..\mathrm{.}0....=$ acknowledgement

TCP: $....0...=$ push

TCP: $....\mathrm{.}0..=$ Reset

TCP: $.....\mathrm{.}1.=$ Syn

TCP: $......\mathrm{.}0=$ Fin

TCP: Window $=8760$

TCP: Checksum $=0$xc$0$c$9$

TCP: Urgent pointer $=0$

TCP: No options

TCP:

TCP: No options

Analyse the above trace and indicate the following:

a$)$ The protocol used in each of the following layers: Data Link, Network, Transport and Application.$[4]$

b$)$ Source and destination MAC addresses$[2]$

c$)$ Source and destination IP addresses.$[2]$

d$)$ Source and destination port numbers.$[2]$

e$)$ Explain the value $0$x$02$ shown in the flags field $($highlighted in blue color in the trace$)$ by indication the type of this captured message?$[2]$

f$)$ Explain the meaning of the value shown in Time to live $=64($highlighted in blue color in the trace$)?[2]$

g$)$ Explain the meaning of the value shown in Protocol $=6($highlighted in blue color in the trace$)$