The "Intro to LAN" room on TryHackMe is a Premium walkthrough that introduces users to the technologies and designs behind Local Area Networks (LANs). While the full content is behind a paywall and cannot be directly reproduced, I can guide you through the general structure and concepts typically covered in this room, based on standard networking knowledge and what TryHackMe usually includes in such modules.
🧩 Task 1: Introduction
LAN topologies refer to the layout or design of a network, and each type has its own strengths and weaknesses. The star topology is the most common today, where each device connects to a central hub or switch. It's reliable and scalable but more expensive due to the extra cabling and hardware. If the central device fails, the whole network is affected. The bus topology uses a single backbone cable to connect all devices, making it cheap and easy to set up. However, it's prone to bottlenecks and has a single point of failure, making troubleshooting difficult. The ring topology connects devices in a loop, requiring less cabling and hardware. It’s easier to troubleshoot but inefficient for data travel and vulnerable to total failure if any part of the loop breaks.
Switches are central devices that connect multiple devices efficiently by sending data only to the intended recipient, unlike hubs that broadcast to all. They are essential in larger networks. Routers, on the other hand, connect different networks and direct data between them using routing. Connecting switches and routers can improve network reliability by providing alternate data paths, even if it slightly reduces performance.
Now we need to complete the puzzle in the View Site section in order to score the flag. It is a very self-teached way to achieve the flag while trying to compromise all topologies
🧩 Task 2: A Primer on Subnetting
Subnetting is the process of dividing a larger network into smaller, more manageable segments called subnets. This is similar to slicing a cake so each department or group—like Accounting, Finance, or HR—gets its own portion. It helps networks efficiently route data to the correct destination, just as you'd send a document to the right department in an office.
Each subnet uses IP addresses in three key ways: to identify the network itself, to identify individual devices (hosts), and to designate a default gateway that connects to other networks. For example, in the IP range 192.168.1.0, the network address might be 192.168.1.0, a host could be 192.168.1.100, and the default gateway might be 192.168.1.254.
While home networks typically use a single subnet due to fewer devices, businesses often require multiple subnets to handle a larger number of connected devices. Subnetting enhances efficiency, security, and control. For instance, a café might use subnetting to separate its internal systems (like cash registers) from the public Wi-Fi, ensuring both security and connectivity.
🧩 Task 3: ARP
ARP (Address Resolution Protocol) is a network protocol that helps devices associate IP addresses with MAC addresses, allowing them to identify and communicate with each other on a local network. Each device maintains an ARP cache—a kind of internal ledger—that stores these associations.
When a device wants to communicate with another, it sends an ARP request to the entire network asking, “Who has this IP address?” The device with that IP responds with its MAC address in an ARP reply. This information is then stored in the sender’s ARP cache for future use, streamlining communication and reducing the need for repeated broadcasts.
🧩 Task 4: DHCP
IP addresses can be assigned to devices either manually or automatically. The most common method is automatic assignment using DHCP (Dynamic Host Configuration Protocol). When a device connects to a network and doesn't already have an IP address, it sends out a DHCP Discover message to locate a DHCP server. The server responds with a DHCP Offer, suggesting an available IP address. The device then replies with a DHCP Request, indicating it wants to use that address. Finally, the server confirms with a DHCP Acknowledgment (ACK), allowing the device to begin using the assigned IP. This process ensures efficient and dynamic IP management across networks.
🧾 Conclusion
The "Intro to LAN" room provides a foundational understanding of how local networks operate, which is essential for anyone pursuing cybersecurity, networking, or IT. By completing this room, you’ve gained:
A solid grasp of network topologies and how devices are structured in a LAN.
Knowledge of IP addressing and subnetting, crucial for managing and segmenting networks.
Insight into DHCP and DNS, which automate and simplify network communication.
An understanding of MAC addresses and ARP, which enable devices to find each other on a LAN.
This room sets the stage for more advanced topics like network scanning, penetration testing, and packet analysis. Mastering these basics ensures you're well-prepared for future challenges in both offensive and defensive cybersecurity roles.
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