Mastering Cybersecurity: Day 8 of the 100-Day Challenge

Basic Introduction To Networks

A network is a group of connected devices. At home, the devices connected to your network might be your laptop, cell phones, and smart devices, like your refrigerator or air conditioner. In an office, devices like workstations, printers, and servers all connect to the network. The devices on a network can communicate with each other over network cables, or wireless connections. Networks in your home and office can communicate with networks in other locations, and the devices on them.

The common devices that make up a network. Let's get started.

A hub is a network device that broadcasts information to every device on the network. Think of a hub like a radio tower that broadcasts a signal to any radio tuned to the correct frequency.

Another network device is a switch. A switch makes connections between specific devices on a network by sending and receiving data between them. A switch is more intelligent than a hub. It only passes data to the intended destination. This makes switches more secure than hubs, and enables them to control the flow of traffic and improve network performance.

Another device that we'll discuss is a router. A router is a network device that connects multiple networks together.

For example, if a computer on one network wants to send information to a tablet on another network, then the information will be transferred as follows: First, the information travels from the computer to the router. Then, the router reads the destination address, and forwards the data to the intended network's router. Finally, the receiving router directs that information to the tablet.

Finally, let's discuss modems. A modem is a device that connects your router to the internet and brings internet access to the LAN.

For example, if a computer from one network wants to send information to a device on another network in a different geographic location, it would be transferred as follows: The computer would send information to the router, and the router would then transfer the information through the modem to the internet. The intended recipient's modem receives the information, and transfers it to the router. Finally, the recipient's router forwards that information to the destination device.

Network tools such as hubs, switches, routers, and modems are physical devices. However, many functions performed by these physical devices can be completed by virtualization tools.

Virtualization tools are pieces of software that perform network operations. Virtualization tools carry out operations that would normally be completed by a hub, switch, router, or modem, and they are offered by cloud service providers. These tools provide opportunities for cost savings and scalability. You'll learn more about them later in the certificate program.

Network components, devices, and diagrams Network devices Network devices maintain information and services for users of a network. These devices connect over wired and wireless connections. After establishing a connection to the network, the devices send data packets. The data packets provide information about the source and destination of the data. This is how the information is sent and received via different devices on a network.

The network is the overall infrastructure that allows devices to communicate with each other. Network devices are specialized vehicles like routers and switches that manage what is being sent and received over the network. Additionally, devices like computers and phones connect to the network via network devices.

Devices and desktop computers Most internet users are familiar with everyday devices, such as personal computers, laptops, mobile phones, and tablets. Each device and desktop computer has a unique MAC address and IP address, which identify it on the network. They also have a network interface that sends and receives data packets. These devices can connect to the network via a hard wire or a wireless connection.

Firewalls A firewall is a network security device that monitors traffic to or from your network. It is like your first line of defense. Firewalls can also restrict specific incoming and outgoing network traffic. The organization configures the security rules of the firewall. Firewalls often reside between the secured and controlled internal network and the untrusted network resources outside the organization, such as the internet. Remember, though, that firewalls are just one line of defense in the cybersecurity landscape.

Servers provide information and services for devices like computers, smart home devices, and smartphones on the network. The devices that connect to a server are called clients. The following graphic outlines this model, which is called the client-server model. In this model, clients send requests to the server for information and services. The server performs the requests for the clients. Common examples include DNS servers that perform domain name lookups for internet sites, file servers that store and retrieve files from a database, and corporate mail servers that organize mail for a company.

Hubs and switches Hubs and switches both direct traffic on a local network. A hub is a device that provides a common point of connection for all devices directly connected to it. Hubs additionally repeat all information out to all ports. From a security perspective, this makes hubs vulnerable to eavesdropping. For this reason, hubs are not used as often on modern networks; most organizations use switches instead. Hubs are more commonly used for a limited network setup, like a home office.

Switches are the preferred choice for most networks. A switch forwards packets between devices directly connected to it. They analyze the destination address of each data packet and send it to the intended device. Switches maintain a MAC address table that matches MAC addresses of devices on the network to port numbers on the switch and forwards incoming data packets according to the destination MAC address. Switches are a part of the data link layer in the TCP/IP model. Overall, switches improve performance and security.

Routers Routers connect networks and direct traffic, based on the IP address of the destination network. Routers allow devices on different networks to communicate with each other. In the TCP/IP model, routers are a part of the network layer. The IP address of the destination network is contained in the IP header. The router reads the IP header information and forwards the packet to the next router on the path to the destination. This continues until the packet reaches the destination network. Routers can also include a firewall feature that allows or blocks incoming traffic based on information in the transmission. This stops malicious traffic from entering the private network and damaging the local area network.

Modems and wireless access points Modems usually connect your home or office with an internet service provider (ISP). ISPs provide internet connectivity via telephone lines or coaxial cables. Modems receive transmissions or digital signals from the internet and translate them into analog signals that can travel through the physical connection provided by your ISP. Usually, modems connect to a router that takes the decoded transmissions and sends them on to the local network.

Note: Enterprise networks used by large organizations to connect their users and devices often use other broadband technologies to handle high-volume traffic, instead of using a modem.

Wireless access point

A wireless access point sends and receives digital signals over radio waves creating a wireless network. Devices with wireless adapters connect to the access point using Wi-Fi. Wi-Fi refers to a set of standards that are used by network devices to communicate wirelessly. Wireless access points and the devices connected to them use Wi-Fi protocols to send data through radio waves, which are sent to routers and switches and directed along the path to their final destination.

Using network diagrams as a security analyst Network diagrams allow network administrators and security personnel to imagine the architecture and design of their organization’s private network.

Network diagrams are maps that show the devices on the network and how they connect. Network diagrams use small representative graphics to portray each network device and dotted lines to show how each device connects to the other. By studying network diagrams, security analysts develop and refine their strategies for securing network architectures.

In conclusion, understanding the basics of networks is essential for both home and office environments, as these systems facilitate communication between a variety of devices. Networks are composed of several key devices, including hubs, switches, routers, and modems, each serving specific functions to manage data traffic and connect different parts of the network. Virtualization tools can also perform many of these functions through software, offering advantages in cost and scalability. Devices like computers, smartphones, and tablets connect to the network and communicate using data packets. Security measures, such as firewalls, protect these networks from unauthorized access. Finally, network diagrams are crucial tools for visualizing and managing the network’s architecture, helping security analysts develop effective security strategies.