Networking: Networking Concepts (TryHackMe)

In this article, I will write a write-up for Networking Concepts that covers OSI Model, TCP/IP Model, IP Addresses and Subnets, UDP and TCP, Encapsulation, and Telnet.

1. Which layer is responsible for connecting one application to another? Layer 4

2. Which layer is responsible for routing packets to the proper network? Layer 3

3. In the OSI model, which layer is responsible for encoding the application data? Layer 6

4. Which layer is responsible for transferring data between hosts on the same network segment? Layer 2

5. To which layer does HTTP belong in the TCP/IP model? Application Layer

6. How many layers of the OSI model does the application layer in the TCP/IP model cover? 3

7. Which of the following IP addresses is not a private IP address?

   • 192.168.250.125

   • 10.20.141.132

   • 49.69.147.197

   • 172.23.182.251 49.69.147.197

8. Which of the following IP addresses is not a valid IP address?

   • 192.168.250.15

   • 192.168.254.17

   • 192.168.305.19

   • 192.168.199.13 192.168.305.19

9. Which protocol requires a three-way handshake? TCP

10. What is the approximate number of port numbers (in thousands)? 65

11. On a WiFi, within what will an IP packet be encapsulated? Frame

12. What do you call the UDP data unit that encapsulates the application data? Datagram

13. What do you call the data unit that encapsulates the application data sent over TCP? Segment

    let’s request a web page using telnet. After connecting to port 80, you need to issue the command GET / HTTP/1.1 and identify the host where anything goes, such as Host: telnet.thm. The output below shows the exchange. (The page has been redacted.)

    Note: You may have to press Enter after sending the information in case you don’t get a response.

    Terminal

    user@TryHackMe$ telnet MACHINE_IP 80Trying MACHINE_IP...
    Connected to MACHINE_IP.
    Escape character is '^]'.
    GET / HTTP/1.1
    Host: telnet.thm
    
    HTTP/1.1 200 OK
    Content-Type: text/html
    [...]
    
    Connection closed by foreign host.
    

    Answer the questions below

14. Use telnet to connect to the web server on MACHINE_IP. What is the name and version of the HTTP server? lighttpd/1.4.63

Remember Telnet replaces ssh so we won’t need the ssh this time. You run telnet ip_address 80 80 since it's HTTP Server . Once you’ve entered type GET / HTTP/1.1 enter then type Host: telnet.thm keep entering till you get an output is the connection closes before you get an output try again

15. What flag did you get when you viewed the page? THM{TELNET_MASTER}

Thank you for reading my article. Please leave any questions or comments on improving my learning journey and the THM challenges. We can also connect more on LinkedIn or X.