Network Devices

Answer 1

When we talk about network devices, what comes to mind first? You’re probably thinking about routers and firewalls, and whilst these are present in essentially every network, there are a number of other devices that are used to create infrastructure within businesses, providing them with IT systems that can communicate and help business operations. Most networks are small, such as your home network and office networks, and even bigger networks are broken down into smaller ones.

We will cover the following network devices in this lesson:

Switch
Router
Hub
Bridge
Firewall

Question 2

Router

Answer 2

A router is a network device that forwards data based on a logical address. In the case of TCP/IP networks, the router would forward data based on the IP addresses of systems. If you’re on your home network and want to visit Google.com, your request will go to the router (DNS will convert the domain name Google.com into the IP address), and your request will be sent over the internet to the Google.com web server IP.

Question 3

Hub

Answer 3

A hub is a network device that connects all devices on a Local-Area-Network or LAN. When a system sends data to the hub on one port, the hub will broadcast these to all other attached devices (see image below). Hubs can be referred to as “dumb” devices because they do not understand who is the intended recipient of the data that has been received, so it sends it to all devices. Although the data will eventually reach the intended system, it generates unnecessary traffic, and can also allow attackers to steal data. If an attacker is connected to a hub, whenever any connected host sends data, it will be sent to every other host, including the attacker’s machine!

Question 4

Switch

Answer 4

A switch works as a smart version of a hub because it actually understands where to send data, instead of sending it to everyone. It achieves this by using MAC addresses as unique identifiers for recipients of incoming data, so it can send it to the right system. In this diagram below, if the Desktop Computer wants to print a document, they would send the request which would reach the Network Switch, which will know to send it to the Printer as the Desktop Computer will include the MAC address in the request (which is gained by using Address Resolution Protocol, or ARP).

Question 5

Bridge

Answer 5

A network bridge device works to connect separate networks to make them into one larger network. This is different than a router, which allows networks to be connected but work independently. In the OSI model, bridging works at Layer 2, the Data Link Layer.

Question 6

Firewall

Answer 6

A firewall is a network device that provides fundamental network security, by monitoring incoming and outgoing traffic and determining whether to allow or block it, based on rules. Firewalls can come in software form or hardware form as physical devices that are plugged into the network infrastructure. This allows us to create private networks, where only intended communications can come in, or out. We have an activity later in the course where you’ll set up your own PfSense firewall to better understand how rules work!