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What is a network?
What is a network?
A network is a group of computers connected together. This allows computers to share resources such as software, files and printers.
Types of Networks
Types of Networks
Personal Area Network (PAN)
Personal Area Network (PAN)
Uses Bluetooth to connect personal devices together like a smartphone and smart watch.
Local Area Network (LAN)
Local Area Network (LAN)
A computer network over a single geographical location like a school, home or business.
Owned by the individual or the company who use it.
Wide Area Network (WAN)
Wide Area Network (WAN)
A large network over a wide area that typically connects LANs together.
Owned by multiple people as they will own each LAN that makes up the WAN.
The internet is the largest example of a WAN.
Wired Vs Wireless Networks
Wired Vs Wireless Networks
Wired
Wired
Wired networks can use two types of cable, copper or fibre.
Copper wired networks are slowly being replaced by fibre (optical) cable networks.
These cables run from homes and businesses to street boxes (ISP boxes) and they then run connections to the ISP's servers to provide an internet connection to the property.
in all instances, fibre optic cables are faster and have less chance of interference than copper cables but copper cables are cheaper.
Pros and Cons of a wired network:
+ More reliable than wireless networks
+ More secure than wireless connections
+ Devices can be portable within the range of the access point
– Need to lay cables
– Connection speed reduces the further the cable has to go (copper)
– Connection can be affected by electrical interference (copper)
Wireless
Wireless
Wireless networks connect using Wi-Fi which is broadcast using radio waves which are part of the microwave spectrum.
Wi-Fi is a trademark used to describe a Wireless LAN or WLAN
A wireless Access Point (AP) is a device that allows wireless devices to connect to a wired network using Wi-Fi.
The AP usually connects to a router via a wired network.
Home Wi-Fi routers often combine the functions of switch, router and wireless access point in one box.
Pros and Cons of a wireless network:
+ No need to lay cables
+ Easy to connect new devices
+ Devices can be portable within the range of the access point
– Can be less reliable than wired networks
– If many devices try to use the same access point at the same time, the connection can be very slow
– Connection speed reduces the further the device is from the access point
– Can be less secure than wired connections
Network Protocols
Network Protocols
A protocol is a rule that is followed to ensure that a process is carried out and carried out correctly. Network protocols are rules used in networks to ensure the communication between devices is carried out correctly.
Protocol
Protocol
Transmission Control Protocol
Internet Protocol
Hypertext Transfer Protocol
Hypertext Transfer Protocol Secure
Simple Mail Transfer Protocol
Internet Message Access Protocol
Acronym
Acronym
TCP
IP
HTTP
HTTPS
SMTP
IMAP
Purpose
Purpose
Controls the transmission of data on the network
Sets the rules around connecting the device to the internet
Transferring data to and from websites
Transferring data to and from websites securely
Protocol for sending emails
Protocol for accessing emails
TCP/IP Model
TCP/IP Model
The TCP/IP model sets out the layers of operation for networks and the sending of data across networks. Each of the above protocols operate on one of the layers.
Layer
Layer
Application layer
Transport layer
Internet layer
Link layer
Purpose
Purpose
Where applications, such as web browsers or email programs, operate.
Sets up the communication between the two hosts and they agree settings.
Addresses and packages data for transmission and routes packets across the network.
Where the network hardware such as the NIC (network interface card) is located. OS device drivers also operate here.
Protocols
Protocols
HTTP, HTTPS, SMTP and IMAP
TCP
IP
Network Security
Network Security
The second you connect a device to a network you open it up to being vulnerable to attack from malicious actors. Networked computers that get infected with a virus or similar malware can spread that virus to any other computer it is connected to on the network.
Becuase of this, we need network security.
methods of network security:
Authentication
Encryption
Firewall
MAC address filtering
These methods can work together to provide a greater level of security.
Authentication
Authentication
Authentication is when a user is asked to verify their identity, usernames and passwords are typical forms of authentication, however, in recent years two-factor authentication (2FA) has become widely adopted where a user is asked to enter a code that has been sent to another verified service like an email or text message.
Encryption
Encryption
Encryption is the encoding of data so that it can no longer be easily understood. For example, encrypting a password entered into a website so that if the input was to be intercepted, it isn't readable.
Encryption Terminology:
Plaintext: the original message to be encrypted
Ciphertext: the encrypted message
Encryption: the process of converting plaintext into ciphertext
Key: a sequence of numbers used to encrypt or decrypt, often data using a mathematical formula
Encryption algorithm: the formula for encrypting the plaintext
Firewall
Firewall
A firewall is a network security device that monitors incoming and outgoing network traffic and decides whether to allow or block specific traffic based on a defined set of security rules. The capabilities of firewalls have changed dramatically in recent years and will continue to do so.
MAC address filtering
MAC address filtering
Every device that is capable of connecting to a network has a Network Interface Card, on that NIC is a MAC address. These are unique identifiers that allow each device that connects to a network to identify itself. As they are unique, MAC address filtering allows devices to access, or be blocked from accessing a network based on their physical address embedded within the device’s network adapter.
If you allow access to certain devices by their MAC address, this is known as a whitelist.
If you deny access to certain devices by their MAC address, this is known as a blacklist.
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