Fundamentals of Networks

?? Welcome to Day 2 of the hashtag#CyberSecurity365 Challenge! Let's break down the fundamentals of networks.

1. What is a Network?

A network is simply a group of devices connected to each other for the purpose of sharing resources like data, files, printers, and internet access. Networks can vary in size, from small local networks (LAN) to large global networks (WAN).

• LAN (Local Area Network): A small, localized network (e.g., within a home or office).
• WAN (Wide Area Network): A network that spans a large geographical area (e.g., the internet).

Key components of a network:

• Devices: Computers, smartphones, printers, etc.
• Network Interface Cards (NICs): Hardware that connects devices to the network.
• Switches & Routers: Facilitate communication between devices on the network.
• Cabling: Ethernet cables or wireless connections that physically connect devices.

2. OSI Model:

The OSI (Open Systems Interconnection) Model is a conceptual framework used to understand and describe how different networking protocols interact. It has 7 layers, each playing a crucial role in network communication:

1. Physical: Hardware transmission of raw data over a medium (e.g., cables, wireless).
2. Data Link: Ensures reliable transmission between devices (e.g., Ethernet).
3. Network: Manages addressing and routing of data (e.g., IP addresses).
4. Transport: Ensures end-to-end communication (e.g., TCP, UDP).
5. Session: Manages sessions or connections between applications.
6. Presentation: Translates data formats (e.g., encryption, compression).
7. Application: Interacts directly with the user (e.g., HTTP, FTP).

3. IP Addressing: Devices Communication

Each device on a network is identified by an IP address. There are two main types of IP addresses:

• IPv4: Written as four decimal numbers (e.g., 192.168.1.1).
• IPv6: A newer format to handle the limited availability of IPv4 addresses (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334).

Subnetting is the practice of dividing a network into smaller subnetworks, which helps in efficient IP address management.

Hands-on task: Try to configure your local network with a static IP address on a computer or router. Here's how you can do it on a Windows machine:

• Go to Network & Internet Settings.
• Select Ethernet or Wi-Fi and click on Properties.
• Under IP Settings, select Edit and configure a static IP.

4. Networking Devices:

Understanding the different devices used to build networks is essential. Here are the primary types:

• Router: Directs data packets between networks (LAN to WAN).
• Switch: Connects multiple devices within a single network and allows communication between them.
• Hub: A basic device that connects multiple devices but lacks intelligence (less efficient than a switch).
• Access Point: Provides Wi-Fi access to the network.

Hands-on task: Set up a home router and connect multiple devices. Observe the router’s configuration page to see how it manages IP addresses.

5. Common Networking Protocols

Protocols are rules that define how data is transmitted over the network. Some of the most commonly used protocols include:

• HTTP (Hypertext Transfer Protocol): Used for web browsing.
• FTP (File Transfer Protocol): Used for file transfers.
• TCP/IP (Transmission Control Protocol/Internet Protocol): The fundamental protocol suite for the internet.
• DNS (Domain Name System): Resolves domain names (like www.example.com) into IP addresses.

Hands-on task:

• Open a Command Prompt (Windows) or Terminal (macOS/Linux).
• Type ping google.com to test your DNS resolution and connection to the internet.
• Try tracert or traceroute to see the path packets take from your device to a server.

6. Wireless Networks and Wi-Fi

Wi-Fi is the wireless communication technology that enables devices to connect to the internet or a local network without cables.

• Wi-Fi Standards: Wi-Fi 4 (802.11n), Wi-Fi 5 (802.11ac), and Wi-Fi 6 (802.11ax) are different generations offering various speeds and capabilities.
• SSID (Service Set Identifier): The name of a Wi-Fi network.
• Encryption: WPA3 is the most secure encryption method for Wi-Fi networks.

Hands-on task:

• Set up a Wi-Fi network on your router and configure security settings (WPA2 or WPA3).
• Use a device to connect to the Wi-Fi and test the network speed using an online tool like Speedtest.net.

7. Basic Network Security

Network security is crucial to prevent unauthorized access, data breaches, and cyber-attacks. Basic concepts include:

• Firewalls: Hardware or software that blocks unwanted traffic.
• Encryption: Protects data privacy during transmission.
• VPN (Virtual Private Network): Secures your internet connection by encrypting your data.

Hands-on task:

• Set up a simple firewall on your router.
• Use a VPN service to test secure browsing from your device.

8. Troubleshooting Network Issues

Network problems are inevitable. Here are some basic troubleshooting steps:

• Ping Test: To check if a device is reachable.
• IPConfig: On Windows, use the ipconfig command to see your IP configuration and renew it.
• Traceroute: To identify where packets are getting delayed or lost.

Hands-on task: Try the ping, ipconfig, and tracert commands to troubleshoot a connection issue.