Networking

LAN

A collection of computers and peripheral devices connected together within a small geographical area. All of the equipment is wholly owned by the business/homes, not leased.

WAN

A collection of computers and LANS connected together over a large geographical area. It used infrastructure/connections leased from the third party.

Protocol

A set of rules that defines how devices communicate.

Hub

Provides physical connectivity to the LAN. Broadcasts all packets to all devices connected to that hub.

Switch

Provides physical connectivity to the LAN. An intelligent device that forwards packets to the appropriate device based on the MAC address.

Peer-to-Peer network

All the computers are equal and share resources. No central server.

Client-server network

Shared files and resources and on centralised servers. The networked PCs are clients that request services from these servers.

The Internet

A global wide are network that uses IP to transmit data.

Router

Connects different networks together - LANs to the internet specifically. Provides a public IP address.

Malware/Virus

Software designed to harm your system in some way eg : delete files. It replicates itself.

Hacking

Unauthorized access to a computer.

Brute Force Attack

Working through all the possible passwords or code numbers until one is successful.

Denial of Service Attack

Attempting to stop legitimate users accessing services or a website by flooding it with messages.

Data interception

Remote theft by accessing accounts using acquired securtiy systems.

SQL injection

Putting SQL code into a database to acquire data e.g. a list of usernames and passwords

Penetration testing

Attempting to break into a systems to identify points of weakness.

Anit-malware software

Prevents harmful prgrams being installed. Detects and removes malware.

Firewall

Hardware or software that protects a network from unarthourised access using filters based on IP addresses, named websites and types of files.

User authentication

Using a username and password to check a user is authorised/who they say they are.

User access levels/rights

Define whether a user can see a file/folder at all, whether they just read from it (RO) or also wrtie to it (RW). Other access rights include write only and execute.

Physical security

This includes locked rooms, CCTV, guards, barrirs etc.

Plain text

The original un-encrypted message.

Cypher text

The encrypted message

Encryption

The process of converting plain text to cypher text, encoding.

Decryption

The process of converting cypher text to plain text, decoding.

Character Set

The set of symbols that can be represented by a comuter. Each character is represented by a unique numerical code that is stored as a binary integer.

ASCII

A character set that uses 7 or 8 btis to encode each character.

Unicode

A character set that uses at least 16 bits to encode each character.