13b Internet Security Flashcards
What is a firewall?
A network security system controlling incoming and outgoing traffic. Acting as barrier between other untrusted networks.
What are the 5 methods used by firewalls?
- Packet filtering
- State full inspection
- Ports
- Ip addresses
- Unusual behaviour
What is packet filtering?
Accepting and blocking packets based on the ip of origin or the protocol being used.
What is stateful inspection?
The packets contents are examined for malicious code. If any is found it is rejected.
How do firewalls use ports?
Blocks ports when they are no longer in use so malicious data isn’t sent through them.
How do firewalls use up addresses?
Unknown IPs are blocked
How do firewalls use unusual behavior to secure networks?
They observe network traffic patterns and if a lot more data than usual comes through the packets are blocked. This prevents DDOS attacks.
What other function do firewalls have?
They keep a log of the entire history of incoming and outgoing data.
What is a proxy server?
A device that acts as a middleman between your computer and the internet. It filters access to websites.
What are the 4 functions of proxy servers?
- Hides IP address
- Content filtering
- Caching
- Tracks internet usage
What is the problem with symmetric encryption?
It relies on the receiver to have the correct key. How should this key be sent to them?
What is symmetric encryption?
When the message is encrypted using a key by the sender and the receiver decrypts using the same key.
How does asymmetric encryption work?
- Sender encrypts with receivers public key
- Receiver decrypts with their private key
What is the best use for asymmetric encryption?
Best used for key exchange as once keys have been exchanged allowing symmetric, symmetric encryption is faster.
How is a digital signature produced?
- The message is hashed (encrypted)
- The message is encrypted with A’s private key
- The original message and the encrypted message (digital signature) are encrypted with B’s public key
- B receives the message and decrypts with their private key
- The digital signature is decrypted with A’s public key
- The
What threats are the three main types of malicious software?
Viruses
Trojan horses
Worms
How do viruses work?
Attaches itself to a file and spreads when interacted with.
How do works work?
Works are independent of the host program and wait until the device connects to a network sand then spreads throughout it. Often used to create botnets.
How does a Trojan horse work?
Disguises itself as useful files to infiltrate. Doesn’t replicate or spread.
Creates backdoors allowing data to be stolen.
What are the methods for defending against viruses and Trojans and worms?
- Configure a proper firewall
- Keep software up to date
- Use a firewall to cloak your device from the network
- Never open emails without scanning with anti virus software
- Regularly scan the device with anti virus software
