Hands-On Linux System Administration

Ransomware is an attack in which criminals gain access to an organisation's systems, encrypt or steal its data, and demand payment to restore access or withhold publication.

A security operations centre is the team, tooling and process that monitors an organisation's systems for security events around the clock, triages alerts, and starts the response to those that are real.

A security risk assessment identifies the threats to an organisation's assets, estimates how likely each is and how much harm it would do, and ranks them so that limited effort goes where it reduces the most harm.

Network address translation rewrites the addresses and ports in packets as they cross a network boundary, most commonly so that many devices with private addresses can share one public address to reach the internet.

DHCP is the protocol by which a device joining a network asks for and receives an address, a subnet mask, a default gateway and DNS servers from a server, for a limited lease period, so that nobody has to configure addresses by hand.

A wireless LAN connects devices to a network over radio using the 802.11 family of standards, through access points that bridge the wireless medium onto the wired network and enforce the authentication and encryption that the shared airwaves demand.

Managed hosting is any plan where the provider runs the server on your behalf, covering updates, hardening, monitoring, backups and tuning, so the thing being sold is administration time with a machine attached rather than the machine itself.

Cloud hosting is the model in which servers, storage and databases are created on demand through an API from a provider's pooled hardware and billed for the time they exist, rather than rented as a fixed box by the month.

A web server is the program listening on a network port for HTTP requests and answering them, either by returning a file from disk or by handing the request to application code behind it.