Internet Security

A piece of software that sits between 2 networks. It can prevent certain things from entering and leaving

When a firewall checks packet headers arriving from untrusted networks against a set of rules or packet filters defined by the network administrator

When the firewall inspects packets to check which port they’re attempting to access

When incoming & outgoing traffic is continuously monitored after a connection is established Done via looking at contents of packet rather than header

Requires the firewall to maintain a connection table which keeps track of all conversations going on between networks

Sits between the client device and firewall. Provides anonymity to the client keeping their true IP hidden.

• keeps a cache of websites, speeds up user access and reduces traffic • logs all user activity e.g. recording a list of websites user has attempted to visit • web filtering

uses the same key for encryption & decryption

• Uses a public and private key. The keys work as a pair. • one key is used to encrypt message and the other to decrypt. • used to initiate TLS connections

• symmetric is faster as it uses less complex mathematical operations, allows for data to be encrypted and decrypted at suitable speeds • Asymmetric is slower but allows the sender to be authenticated (more secure)

When the communicating devices have to transfer the key between them so they can pass each other messages

A form of authentication to guarantee the integrity of the message and authenticate the sender

• runs a hash function against the unencrypted message to produce a hash total • encrypts the hash total with their private key, forming the digital signal • the sender then bundles it with the message and encrypts it with the public key

• uses private key to decrypt the bundled digital signature & message • use the public key to decrypt hash total • run the hash function on the plaintext to see if it matches the hash total • if the hashed message and hash total match then it verifies the integrity

A timestamp so that a false signature cannot be recreated at a later date

An electronic document that authenticates a message sender or website • issued by an official certificate authority

• serial number • expiry date • holder’s name • holder’s public key • ‘signed’ by digital certificate of issuing CA to verify its genuine

• used to verify the identity of the owner of each public key and obtain the key itself • used to check if a website is authentic • used by websites that use HTTPS

• Human weakness • out of date or unpatched software • poor code quality

• Malicious form of self-replicating software • attaches itself to other programs or files • makes copies of itself and spread to infect computer systems

May be designed to: Spam / steal data / infect other devices on network / corrupt files

Malicious software that can replicate and distribute itself independently. Done by using network features or email services to spread

• programmed to damage software • waste system resources

Uses up network bandwidth, slows down network significantly Some cases worms can use all the resources causing a denial-of-service attack