This series of walkthroughs aims to help out complete beginners with finishing the Pre Security Path on the TryHackMe (thm)1 website.

It is based on the learning content provided in the Extending Your Network room.

Task 1 - Introduction to Port Forwarding

Check out how port forwarding works, and why it is so essential for network communications.

Question 1: What is the name of the device that is used to configure port forwarding?


Task 2 - Firewalls 101

Read about the differences between a stateful and a stateless firewall.

Question 1: What layers of the OSI model do firewalls operate at?

Layer 3,Layer 4

Question 2: What category of firewall inspects the entire connection?


Question 3: What category of firewall inspects individual packets?


Task 3 - Practical - Firewall

The flag will present itself, after you successfully, and correctly configured the firewall found on the attached static site. Your goal is to prevent a device from overloading by adding the appropriate firewall rule to the router in the middle.

Firewall - 1

Configure the router to drop all packets accessing our web server (port 80) from the attacker’s machine. (IP -

Firewall - 2

Firewall - 3

Question 1: What is the flag?


Task 4 - VPN Basics

Make yourself comfortable with VPN technology, and check out the advantages it can provide. Read about it’s various technologies before moving on to the next task.

Question 1: What VPN technology only encrypts & provides the authentication of data?


Question 2: What VPN technology uses the IP framework?


Task 5 - LAN Networking Devices

The different LAN networking devices like routers and switches are introduced here.

Question 1: What is the verb for the action that a router does?


Question 2: What are the two different layers of switches? Separate these by a comma I.e.: LayerX,LayerY


Task 6 - Practical - Network Simulator

The network simulator attached to this task will break down the communication between two points, and displays it graphically. Play around a bit with it, and get a better understanding how exactly the communication happens.

Routing - 1

Send a TCP packet from computer1 to computer3 with the help of the switches and the router on the path connecting them.

Routing - 2

After our packet was received on computer3, a pop-up window provides us with the flag.

Routing - 3

Check out the network log that was created after sending a single TCP packet from computer1 to computer3.

StepConnection typeNetwork log
1HANDSHAKEStarting TCP/IP Handshake between computer1 and computer3
2HANDSHAKESending SYN Packet from computer1 to computer3
3ROUTINGcomputer1 says computer3 is not on my local network sending to gateway: router
4ARP REQUESTWho has router tell computer1
5ARP RESPONSEHey computer1, I am router
6ARP REQUESTWho has computer3 tell router
7ARP RESPONSEHey router, I am computer3
8HANDSHAKEcomputer3 received SYN Packet from computer1, sending SYN/ACK Packet to computer1
9HANDSHAKEcomputer1 received SYN/ACK Packet from computer3, sending ACK packet to computer3
10HANDSHAKEcomputer3 received ACK packet from computer1, Handshake Complete
11TCPSending TCP packet from computer1 to computer3
12TCPcomputer3 received TCP Packet from computer1, sending ACK Packet to computer1

With this, we arrived at the end of this room. This also marks the completion of the Network Fundamentals module.

Question 1: What is the flag from the network simulator?


Question 2: How many HANDSHAKE entries are there in the Network Log?


  1. thm - shorthand for TryHackMe from now on ↩︎