A network of interconnected computer networks, which use a common end-to-end protocol (TCP/ IP).

Mostly wired, with cables which pass under oceans to connect many continents.

Internet Service Provider, is a company which provides access to the internet. Larger national ISPs provide internet access to smaller, regional and local ISPs. Customers mostly interact with local ISPs.

A network where data is split into multiple parts called packets. Where each packet may take its own route to its destination, as each packet takes the fastest pathAnd packets are reassembled by the recipient/

A router uses the recipient address on each packet to determine which router to send the packet next for its next hop.

Time to Live, is the number of hops the packets can take, before being deleted and a request for retransmission is sent to the sender.

1. Sender's IP address.
2. Receiver's IP address.
3. Packet contents.
4. TTL number.
5. Sequence number.

The router keeps a table relating to latency between other routers, which is frequently updatedIt uses this data and an algorithm such as Dijkstra's to determine the fastest path.

A gateway will strip each packet of its headers, leaving just the content. This enables new headers to be set, which enable the packet to conform to many different transmission protocols.

A uniform resource locator is used to assign a unique readable address to files on servers connected to the internet.

A string of alphanumeric characters, which aim to be memorable and identify an individual or an organisation on the internet. Each domain is mapped to the IP address of a computer.

A Fully Qualified Domain Name, is domain which species that an exact resource can only be interpreted one way. Rules such as always including the servers host name are requisite.

A domain name server (DNS) contains a table of domains and related IP addressesThe DNS will accept requests to translate domain names, and reply with IP addresses.

Domain name is stored on a smaller domain name servers. A request for corresponding IP address must form multiple hops to be resolved.

Global organisations protect the fast depleting resource of unallocated IP addresses.

Replace a previously unused IP address, rather than distribute a new IP address

Hardware or software which sits between a router and the internet, to regulate which packets pass into and out of the private network, by acting as a proxy server. These proxy servers employ two main methods: packet filtering, stateful inspection.

A server which sits between a public network and a private network, which controls the movement of packets out of and into the private network. Provides some anonymity, as the private IP is send out of the private network

Accepts and blocks packets based upon their source IP address or port number. May be manual or automatic using blacklists.

Examination of the contents of the packet, in order to identify suspicious packets.Recording the current connections in a network, for activity based filtering.

Both the sender and receiver share the same private key.The private key is used to both encrypt and decrypt the data.

Sender and receiver must participate in private key exchange, which is vulnerable to interception.

1. Four different keys are used.
2. Both the sender and the receiver have a pair of keys.
3. One key from each pair is private and the other public.
4. The keys are mathematically related.

1. Messages are encrypted with the public key, but can only be decrypted by a corresponding private key.
2. Messages are encrypted with the recipients public key, so that only the recipient can decrypt the message.

Verifies the sender of the message is who he say he isVerifies that the message has not be tampered with.

1. A digest of the message is created using a hashing algorithm or a checksum, based on the contents of the message
2. The digest is encrypted with the sender private key, meaning anyone can decrypt the digest using the senders public key.
3. The encrypted digest is appended to the message.
4. Both the encrypted digest and the message are encrypted with the recipients public key, meaning only the recipient can decrypt the whole message.
5. The recipient decrypts the whole message using its own private key.
6. The recipient decrypts the digest using the senders public key.
7. The same hashing algorithm or checksum is used to recalculate the digest, and see if it matches.

Verifies ownership of key pair used in asymmetric encryption.

Issued by a certificate authority, which ensures validity, each certificate contains: serial numberowner's, name, expiration date, owner's public key,authorities digital signature.

software designed to disrupt, damage, or gain unauthorized access to a computer system.

Worms, trojans, viruses.

Malware which can self-replicate, spread through a network by downloading and autorunning.

Malware disguised as a benign file, which the user is tricked into running - most often received as email attachments or malicious websites.

Malware which requires a host file in which to reside - typically executables. It will lie dormant until file is opened or program is run. It has the ability to spread through file sharing on a network or physical media, but not by itself

1. Train employees on social engineering methods within emails etc.
2. Install anti-malware software to detect and quarantine malware.
3. Update out-of-date software.
4. Write good code, enforce programming practices which reduce the likelihood of bugs being shipped to production environments, so malware cannot exploit flaws.