Computer networking is a vital skill set for many careers. It is also useful for everyday use, as it lets you connect to devices like printers, smart TVs, and refrigerators.
The simplest network consists of two computers connected by a crossover cable. It uses a special media access control (MAC) address to communicate.
Networks
Networks are a collection of devices (computers, routers, switches, and other hardware) that communicate to share data and resources. They can be wired or wireless, with most networks using a mix of both.
Information sent to and from a device in a network is encoded with a unique address called an IP (Internet Protocol) address. This address is used to identify the node sending or receiving the data. The address is determined by the routing protocols that tell the node where to send the packets and how to route them.
Computers in a home network use structured wiring to manage voice, data, and video. They connect to a central system that allows you to control and configure the network. This type of residential application is often referred to as a smart home.
What is network access? NAC solutions allow administrators to determine the security compliance of endpoints on the network before and after connecting to the network. They use pre-admission controls to deny access to a network to devices that don’t meet policy conditions like patch levels, software versions, or other factors. After a device is on the network, it can deny or grant access to specific applications based on user, time of day, and other criteria.
Routers
Routers are networking devices that forward information between networks and the Internet. Essentially, they are like the air traffic control towers of the Internet. With data packets zooming everywhere across different networks, routers ensure those packets reach their intended destination.
Using routing protocols and algorithms, routers work out the fastest data path between unique IP addresses within a network by evaluating each available network connection’s metric value. Then, they send data along the path with the lowest metric value.
As well as being used to forward data packets, routers can perform other networking functions. For example, they can implement Network Address Translation (NAT), which allows multiple devices on a private local area network to share the same external public Internet IP address.
Home routers also allow people to create a private computer network between multiple devices, such as laptops, tablets, phones, printers, and other peripherals. This works through either hard-wired connections or WiFi signals in the case of wireless routers. In a business, a router allows employees to communicate with each other and share resources over long distances.
Switches
Network switches are a critical piece of equipment that connect devices. They work by processing data packets and forwarding them to their intended destination(s). They are used to create a local area network or LAN.
Network protocols translate streams of 1s and 0s into packets sent between devices. Each packet contains a header and payload. The headers contain the addresses of devices communicating, and the payloads contain the actual data.
Switches check each incoming frame for the source MAC address and populate their MAC address table. They then use the table to advance each frame toward its destination intelligently.
Switches also filter traffic flow by preventing certain devices from connecting. For example, a switch can block traffic from specific machines from accessing a server by filtering out the destination MAC address. If the MAC address does not match any entry in the MAC address table, the switch will flood that frame out to all ports except the port where it received the frame (a process known as frame flooding). The goal is for the device with the MAC address to receive the frame and respond.
Firewalls
Firewalls are cybersecurity tools that monitor incoming and outgoing network traffic, permitting or blocking data packets based on security rules. When someone decides to implement a firewall, they often have a good idea of what it should do; however, they need to translate this concept into a series of technical statements called a firewall ruleset.
The firewall ruleset can include policies for both host-based and network-based firewalls. A network-based firewall can control communications amongst a group of hosts. In contrast, a host-based firewall is installed on individual computers to control the activity within them.
A firewall is a guard at the gate of your computer network. All information that travels over the Internet is assembled into a data packet containing the sender, destination address, and port number. The firewall looks at each of these data packets to determine where they’re going and who they are from and then decides a data packet that reaches the intended destination may be allowed through, while one that is not will be denied or dropped.
Internet
Most of us connect to multiple networks every day. When we turn on a computer or mobile device, it automatically connects to a local WiFi network and, in most cases, the Internet (a combination of many networks). Network configuration is the set of rules that define how devices communicate with each other and how they access information, resources and services over a network.
The simplest network is two computers wired together using a special crossover cable. Each computer has a unique address that allows it to find the other on the network. Each computer can communicate over the network by sending data to each other’s MAC addresses, which the router assigns when the computer connects to the router.
Understanding how your users access your network helps you to control and secure it better. It tells you who connects, from where, and with what devices. It also gives you insights into how and when they connect so you can prioritize and distribute bandwidth more efficiently. You can also limit the types of applications, services, or time zones that authenticated devices can access.