Network Protocols and Security Information 2022

Running head: NETWORK PROTOCOLS AND SECURITY
Network Protocols and Security
Name of the Student
Name of the University
Author Note

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NETWORK PROTOCOLS AND SECURITY
1) The text shows how transport segments fit into internet packets which fit into link
layer frames. The Ethernet standard for example adds a frame header and a frame
trailer (see pg. 30). However, there is a physical layer beneath the data link layer and
different standards exist for different media. These include copper wire or optical fiber
as shown in Figure 1-21 (pg. 27). Do different physical standards require additional
headers and/or trailers to be placed around a data link frame header or trailer?
Explain your answer.
Yes, physical standards require additional headers and/or trailers to be placed around a data
link frame header or trailer.
IP protocol of the network layer deals with fragmentation and provides the
fragmentation offset and the identifier. Fragmentation in the network layer involves turning
one IP packet into multiple IP packets. At a time there exists one transport layer and a
network layer for every smaller IP packet.
When routing decisions are made for any given packet, the packet is scheduled to get
transmitted over a specific interface. If this packet happens to be bigger than the MTU
supported by the link, it gets broken into multiple IP packets with the fragment details. The
first fragment contains beginning part of the packet consisting of the TCP header (Kota et al.
2016). Whether there further fragments is known by the receiver by the more fragments flag
and the destination is known by the fragment offset.
Data Link layer adds information in layer 2 header and trailer for example Frame
Check Sequence or FCS for ensuring that data does not get corrupted, and transmits it to the
Physical layer or layer 1 for transmitting over the media.

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2) For the Domain Name System (DNS), what would happen if a malevolent system
acted as a DNS server and returned the IP address of a target system whenever the
address of a popular system (e.g. Facebook or the FIT web site) is requested?
When malevolent systems act as DNS servers and return IP addresses of target
systems with every request to a popular system like that of Facebook or FIT web site, DNS
Spoofing is found to occur. Here the attackers change the data stored in resolver cache of
DNS servers adding incorrect IP addresses to DNS resolver for diverting the connection to
the infected systems.
3) Assume you are operating within a single network (a "local area network" or
"LAN"). Is it possible to exchange information between hosts without using internet
"packets" and transport "segments"? Explain your answer.
Yes, it is possible to exchange information between hosts without using internet "packets"
and transport "segments".
To make two of the computers communicate through the same network these must be
interacting using the same protocol of the network layer. These can be IPv4, IPv6, IPX as
well as X.25 (Giesen et al. 2018). Assuming this to be IPv4 - the commonly used protocol,
these computers will be needing appropriate IP addresses which is usually done manually for
two or three clients.
When the destination system receives the packet, the packet is first examined to check
if the L2 address is matching with L2 address of the physical interface receiving this packet.
If a match is found, it verifies the L3 address also matches what is assigned to the physical
interface.

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4) It is noted (pg. 22) that the transport processes address packet sequencing (ordering
packets should they arrive out of order). Could this function be handled by the
internet processes instead? Why or why not?
Yes, the transport process can be handled by internet processes specifically for remote
systems.
Packet sequencing involves synchronize and acknowledge packets between the host and the
server and acknowledge from the client. The packet delivery can occur two key ways – Local
Packet Delivery and Remote Packet Delivery. When exchanging information with remote
systems present in different networks, we are dealing with remote packet delivery. For
acquiring information like web requests with the remote servers, the IP address of the remote
system will be required. IP addresses of websites can be known from several resources
available over the web.
5) Is it possible for the Transmission Control Protocol (TCP) or the User Datagram
Protocol (UDP) to operate with a different internet protocol than IP? If so, what would
be required? Why might one do this? Hint: Consider the protocol stack.
The TCP or UDP protocols are set of protocols of the TCP/IP model (Samain et al.
2017). This model only uses the Internet Protocol (IP) in its network layer. Hence, usually it
is the IP protocol that is used.
Now the network layer protocols can also include HTTP (Hypertext Transfer
Protocol) and FTP (File Transfer Protocol) (Wei, Hong and Shi 2016). Therefore, Instead of
IP, FTP can be used with TCP UDP operations. FTP uses TCP port 21 which needs to be
configured (Muelas et al. 2017). This is used for more effective file sharing services over the
network.

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6) Messages can be divided into three types based on the intended number of recipients:
a unicast (single source to single known destination), a multicast (single source to
multiple known destinations), and a broadcast (single source to all destinations, known
or unknown). Why is a broadcast employed when a client sends a dynamic host
configuration protocol (DHCP) request message?
DHCP clients broadcasts DHCPDISCOVER messages on network subnets using the
destination address 255.255.255.255 or limited broadcast that is specific subnet broadcast
addresses. DHCP clients can even request last known IP addresses. Thus when these clients
stay connected to the network, servers can grant the request. When clients do not have IP
addresses set, the server is set up only if it is authoritative.
7) Assume you have two different hosts connected to the same switched Ethernet.
However, instead of the internet protocol (IP), one host uses "Tom's Internet Protocol
(TIP)" and the other uses "Rick's Internet Protocol (RIP)". A host using RIP can not
understand a message sent using TIP and a host using TIP can not understand a
message sent using RIP. They use the same Ethernet local area network (LAN).
However, are they really on the same network? Explain your answer.
The two networks using different internet protocols Rick’s Internet Protocol (RIP)
and Tom’s Internet Protocol (TIP) cannot be connected to the same switched Ethernet over
say IP network. For it would require RIP over TCP to be created or TIP over TCP so that the
hosts can understand messages of IP protocol for example X.25 over TCP/IP is carried out
using XOT. Only then the RIP network and the TIP network can be tunnelled through the IP
cloud ensuring that messages can be sent from one set of hosts to the other. However the

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transmission will always fail as the hosts cannot understand the messages created with
different internet protocols.
8) Is it possible for a host to concurrently act as a client and server? Is it possible for an
application to concurrently act as a client and a server? Explain your answers.
Hint: A "receive" operation can be either blocked or unblocked. A blocked receive
will stop (block) until a message is actually received. A non-blocked receive will return
a message if it is available but will otherwise immediately return a "no message" status
and thus, allow the receiver to perhaps do other work and perhaps check for the
message at a later time. A sender can await a response by either using a blocking or
non-blocking receive operation.
Hosts are referred to any node existing in the network. In this network, the host is able
to serve as a client, a server or even both. Servers are computers that have software
applications which allow them in receiving requests from clients and provide various services
like email. Clients are computers with software applications allowing them in sending
requests to server for example use of web browser to access mailing domain.
These hosts can serve the role of clients and servers in the same network at the same
time that is providing certain services to some clients in the network as also requesting
services from other hosts in the network.
9) Assume the existence of a single device such as a rain gauge that is connected via a
radio network. The device only runs a single application that is embedded in read-only
memory (ROM) where the internet protocol (IP) address is provided using 32 physical
switches. The device normally sends one very short message per hour to a known
recipient whose address is also provided using 32 physical switches. However, the
device also has a receiver that should a specific message request be received, the device

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will provide up-to-date information. The device uses the User Datagram Protocol
(UDP). What internet protocol (IP) is the device (likely) using? Assuming no physical
assess, could such a device be used in a Mirai Distributed Denial of Service (DDOS)
attack? Why or why not? Be sure to fully explain your answer.
Real time protocol or RTP is the networking protocol which can be used in this
scenario. RTP is a sub-layer protocol that overlaps UDP. This protocol supports real time
data transfer among participants of the session (Patti, Leonardi and Bello 2016). These
sessions are defined through RTP port number, RTCP Real Time Control Protocol port
numbers, Participant IP addresses and RTP transport which include source, relay, and
receiver. The relay is marked as synchronization source.
It becomes easier for the Mirai DDOS attack to infect the involved devices that can
range from routers to IP cameras as they make use of the Linux family of operating systems.
The attack converts the devices into remotely controlled bots and can be controlled as per the
wishes of the attacker.
10) Assume the rain gauge in question #9 does not send messages exactly on each one
hour period but instead varies the period by a few minutes (earlier or later) based on
the (probably incorrect) current time and date. Why would it do this? Does it matter
if the current time and date are right? What property must the clock (for the time and
date) have? Also, why would the rain gauge be sending a message at all? Could it not
just respond when a request is received? Explain your answers.
Through Real Time Protocol or RTP, the sender transmits RTP payloads at any point
of time. The payload type is not intended for multiplexing different streams of media and
hence it does not matter if the rain gauge is emitting messages at the wrong current time and

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date. The clock must. Measuring section must consist of a float and recording pen attached
and a clock-driven drum so a trace can be marked.
The rain gauge is supposed to send message to help take note of the rain monitoring
data along with rain level and temperature data that it picks up every minute.

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References
Giesen, H., Shi, L., Sonchack, J., Chelluri, A., Prabhu, N., Sultana, N., Kant, L., McAuley,
A.J., Poylisher, A., DeHon, A. and Loo, B.T., 2018, August. In-network computing to the
rescue of faulty links. In Proceedings of the 2018 Morning Workshop on In-Network
Computing (pp. 1-6). ACM.
Kota, S., Goyal, M., Goyal, R. and Jain, R., 2016. Multimedia satellite networks and TCP/IP
traffic transport. arXiv preprint arXiv:1603.08020.
Muelas, D., de Vergara, J.E.L., Ramos, J., García-Dorado, J.L. and Aracil, J., 2017, May. On
the impact of TCP segmentation: Experience in VoIP monitoring. In 2017 IFIP/IEEE
Symposium on Integrated Network and Service Management (IM) (pp. 708-713). IEEE.
Patti, G., Leonardi, L. and Bello, L.L., 2016, October. A Bluetooth low energy real-time
protocol for industrial wireless mesh networks. In IECON 2016-42nd Annual Conference of
the IEEE Industrial Electronics Society (pp. 4627-4632). IEEE.
Samain, J., Carofiglio, G., Muscariello, L., Papalini, M., Sardara, M., Tortelli, M. and Rossi,
D., 2017. Dynamic adaptive video streaming: Towards a systematic comparison of icn and
tcp/ip. IEEE Transactions on Multimedia, 19(10), pp.2166-2181.
Wei, P., Hong, Z. and Shi, M., 2016, June. Performance analysis of HTTP and FTP based on
OPNET. In 2016 IEEE/ACIS 15th International Conference on Computer and Information
Science (ICIS) (pp. 1-4). IEEE.