Methods of Securing a Network (Edexcel IGCSE ICT): Revision Note

Usernames & Passwords

How does a password help?

• Passwords are a digital lock to prevent unauthorised access to an account

• Passwords are used to authenticate a user to the network

• They are often stored as an encrypted/ciphered text entry in a database, ensuring that even with unauthorised access to a database, a hacker would not be able to gain access to the individual passwords of users

• Strong passwords and regular password changes are important to maintain security

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

  • Hardware firewalls will protect the whole network and prevent unauthorised traffic

  • Software firewalls will protect the individual devices on the network, monitoring the data going to and from each computer

Encryption

What is encryption?

• Encryption is a method of scrambling data so that unauthorised users cannot understand it

• Encryption methods use 'keys', which are specialised programs designed to scramble or unscramble data

• Encryption uses complex mathematical algorithms to scramble the data

• There are two common methods of encryption:

  • Symmetric

  • Public key

Symmetric encryption

• The sender uses a key to encrypt the data before transmission

• The receiver uses the same key to decrypt the data

• It's usually faster, making it ideal for encrypting large amounts of data

• The significant downside is the challenge of securely sharing this key between the sender and receiver

• If an unauthorised user captures the key, they can decrypt all messages intercepted in transmission

Public key encryption

• Public key encryption uses two keys:

  • a public key for encryption

  • and a private key for decryption

• Receivers openly share their public key

• Senders use this public key to encrypt the data

• The receiver's private key is the only key that can decrypt the data and is kept locally on their side

• The public and private keys are created at the same time and are designed to work together in this way

• It is typically slower than symmetric encryption

• It is generally used for more secure and smaller data transactions, e.g. passwords, bank details

WEP/WPA

What is WEP?

• Wireless Encryption Protocol (WEP) is a method of encrypting data being transmitted on a wireless network

• Each device on the network uses the same key to encrypt and decrypt data

• It is a less secure encryption method due to all devices on the network sharing the same key

• Eavesdropping software (packet sniffers) can be used to intercept data packets and identify the key

What is WPA?

• Wi-fi Protected Access (WPA) is a more secure method of encrypting data being transmitted on a wireless network

• Each device connected to the network receives a different key

• New keys are used for every packet transmitted on the network

Virtual private networks (VPN)

What is a VPN?

• A VPN allows users to remotely connect to private local area networks (LANs)

• All data sent and received using a VPN is encrypted

• Common uses of a VPN include:

  • Remotely accessing a companies network (working from home)

  • Making secure payments

  • Hiding web activities

  • Bypassing geolocation rights management or online censorship

File access rights

What are file access rights?

• File access rights can be set to determine different levels of access to specific files/folders

• Examples of file permissions include:

  • Read - can read the contents of a file only

  • Write - can make changes to file contents and/or create new files

  • Delete - can delete files

  • Execute - can run applications/launch software

Transaction logs & backups

What is a transaction log?

• A transaction log is a secure file on a network that keeps a record of every action performed by devices on a network

• Transactions logs include:

  • Device & data access

  • Timestamps

  • User IDs

  • Successful/failed login attempts

• Transaction logs don't directly protect a network, they help administrators monitor any identify any unusual activity

• Backups are another indirect method of protecting a network

• Keeping copies of data in a secure place on the network in the event of a data breach/loss