Network Security (AQA GCSE Computer Science)
Revision Note
Written by: Robert Hampton
Reviewed by: James Woodhouse
The Need for Network Security
Why do we need to protect a network?
As technology continues to advance at a rapid rate, sensitive data is increasingly stored on networks making it a target for hackers
Computer networks face a variety of threats and they can cause a large number of issues for a network
The main methods of securing networks are:
Authentication
Encryption
Firewalls
MAC address filtering
Authentication
What is authentication?
Authentication is the process of using credentials to check if a user is who they say they are
Credentials are typically:
Usernames & passwords
ID badges
Access/security codes
Biometrics (finger prints, retina, voice etc.)
Credentials are verified to see if they match what is stored by the system
When can authentication be used?
Authentication is used in computer systems when data or services require approved access, and should not be available to everyone
Examples include:
Logging into networked computers (i.e. school, office etc.)
Accessing online services (i.e. banking, social media, entertainment streaming platforms etc.)
Encryption
What is encryption?
Encryption is a method of converting plain text into ciphered text to be stored
Encryption uses complex mathematical algorithms to scramble the text
Asymmetric encryption, also known as private key, public key encryption is often used for web pages and other communication
When can encryption be used?
Encryption should be used in any situation where sensitive data is being transmitted across a network
Examples include:
Passwords
Bank details
Personal information
Firewalls
What is a firewall?
A firewall is a barrier between a network and the internet
A firewall prevents unwanted traffic from entering a network by filtering requests to ensure they are legitimate
It can be both hardware and software and they are often used together to provide stronger security to a network
When can a firewall be used?
Hardware firewalls can be used to protect a whole network and prevent unauthorised traffic, they usually come built in to a router
Software firewalls can be used to protect an individual device on the network, monitoring the data going to and from each computer, they are usually installed as part of the operating system
MAC Address Filtering
What is MAC address filtering?
MAC address filtering is the process of using a devices MAC address to determine if a device can or cannot connect to a network
Devices with MAC address that are allowed to connect are placed on a ‘white list’, and those not allowed on a ‘black list’
If a device tries to connect to a network and the MAC address is not on the list, connection is refused
A MAC address is a unique identifier embedded into a device during manufacturing
MAC addresses are given to any device capable of connecting to a network, wired or wirelessly
When can MAC address filtering be used?
MAC address filtering is predominantly used on wi-fi networks to limit access to the network to only devices on the ‘white list’
Only approved physical devices can connect to the network
Worked Example
Describe one security measure that could be used, in addition to a password, to make sure that a user is who they are claiming to be [2]
Answer
1 mark for method, 1 mark for valid expansion
A code can be sent to your phone as a (text) message/in an email/as a pop-up to one of your devices...
the user then types in the code (as well as the password) any hacker would need to access the phone as well as the password
An authenticator app on a mobile phone...
this generates a code which the user uses to complete the log-in
Use two-factor authentication/2FA // strong customer/multi-factor authentication...
this asks for a second form of identification such as something you know/possess/are
Biometrics...
(to be authenticated) reference data is compared to the individual’s (unique) biometric data
Smart cards/fobs....
the user inserts a Smart Card to a reader and enters the PIN, the authentication request is then verified (using digital certificates)
Ask security / memorable question...
the user is asked a question that only they know the answer to
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