THM | OSI Model

Network Fundamentals | OSI Model | Summary:

This series of walkthroughs aims to help out complete beginners with finishing the Pre Security Path on the TryHackMe website. It is based on the learning content provided in the OSI Model room.

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Disclaimer: Please note that this write-up is NOT intended to replace the original room or its content, but rather serve as supplementary material for those who are stuck and need additional guidance. This walkthrough provides one (of the many) possible solution to the challenges, without revealing any flags or passwords directly.

Task | 1 | What is the OSI Model?

The OSI Model and it's layers are introduced here. My go-to word for remembering the layers is: Please Do Not Throw Sousage Pizza Away.

First Letter	Layer	OSI Layer number
P - Please	Physical	1
D - Do	Data Link	2
N - Not	Network	3
T - Throw	Transport	4
S - Sousage	Session	5
P - Pizza	Presentation	6
A - Away	Application	7

Here is an other one: All People Seem To Need Data Processing. Use whichever suits you better.

Question 1: What does the "OSI" in "OSI Model" stand for?

Open Systems Interconnection

Question 2: How many layers (in digits) does the OSI model have?

7

Question 3: What is the key term for when pieces of information get added to data?

encapsulation

Task | 2 | Layer 7 - Application

The application layer is presented here.

Question 1: What is the name of this Layer?

Application

Question 2: What is the technical term that is given to the name of the software that users interact with?

Graphical User Interface

Task | 3 | Layer 6 - Presentation

The presentation layer is introduced here.

Question 1: What is the name of this Layer?

Presentation

Question 2: What is the main purpose that this Layer acts as?

Translator

Task | 4 | Layer 5 - Session

Introduction to the session layer.

Question 1: What is the name of this Layer?

Session

Question 2: What is the technical term for when a connection is successfully established?

Session

Question 3: What is the technical term for "small chunks of data"?

Packets

Task | 5 | Layer 4 - Transport

Make yourself familiar with TCP and UDP. (The poor dog...)

Question 1: What is the name of this layer?

Transport

Question 2: What does TCP stand for?

Transmission Control Protocol

Question 3: What does UDP stand for?

User Datagram Protocol

Question 4: What protocol guarantees the accuracy of data?

TCP

Question 5: What protocol doesn't care if data is received or not by the other device?

UDP

Question 6: What protocol would an application such as an email client use?

TCP

Question 7: What protocol would an application that downloads files use?

TCP

Question 8: What protocol would an application that streams video use?

UDP

Task | 6 | Layer 3 - Network

Introduction to the network layer.

Question 1: What is the name of this Layer?

Network

Question 2: Will packets take the most optimal route across the network? (Y/N)

Y

Question 3: What does the acronym "OSPF" stand for?

Open Shortest Path First

Question 4: What does the acronym "RIP" stand for?

Routing Information Protocol

Question 5: What type of addresses are dealt with this layer?

IP Addresses

Task | 7 | Layer 2 - Data Link

Get familiar with the data link layer.

Question 1: What is the name of this layer?

Data Link

Question 2: What is the name of the piece of hardware that all networked devices come with?

Network Interface Card

Task | 8 | Layer 1 - Physical

Finally, the easy and simle physical layer.

Question 1: What is the name of this Layer?

Physical

Question 2: What is the name of the numbering system that is both 0's and 1's?

Binary

Question 3: What is the name of the cables that are used to connect devices?

Ethernet Cables

Task | 9 | Practical - OSI Game

Escape the OSI dungeon by climbing the levels in the correct order and grab the flag.

Question 1: Escape the dungeon to retrieve the flag. What is the flag?

<flag>

Task | 10 | Continue Your Learning: Packets & Frames

Forward to the next room in the module!

Question 1: Join the Packets and Frames room.

No answer needed