Cybersecurity Glossary

Unix is a popular multi-user, multi-tasking operating system developed at Bell labs in the early 1970s by Ken Thompson, Dennis Ritchie, and others. Unix was designed to be a small, flexible system used exclusively by programmers.

A uniform resource locator (URL) is the global address of documents and other resources on the world wide web. The first part of the address indicates what protocol to use, and the second part specifies the IP address or the domain name where the resource is located. A URL is a specific type of uniform resource identifier (URI), although many people use the two terms interchangeably. A URL implies the means to access an indicated resource, which is not true of every URI. URLs occur most commonly to reference web pages (http), but are also used for file transfer (FTP), email (MAILTO), database access (JDBC), and many other applications.

A user contingency plan is the alternative method of continuing business operations if its systems are unavailable.

A uniform resource identifier (URI) is a string of characters that are used to identify the name of a resource. Such identification enables interaction with representations of the resource over a network (such as the world wide web) using specific protocols. In other words, URL is the generic term for all types of names and addresses that refer to objects on the world wide web.

The user datagram protocol (UDP) is a communication protocol that, like tcp, runs on top of ip networks. The protocol was designed by David P. Reed in 1980 and formally defined in RFC 768. UDP uses a simple connectionless transmission model with a minimum protocol mechanism. It is used primarily for broadcasting messages over a network. UDP uses the internet protocol to get a datagram from one computer to another but does not divide a message into packets (datagrams) and reassemble it at the other end. UDP doesn’t provide sequencing of the packets that the data arrives in.

A user is any person, organization entity, or automated process that accesses a system, whether authorized to do so or not. Users generally use a system or a software product without the technical expertise required to fully understand it.

An unprotected share is a mechanism that allows a user to connect to file systems and printers on other systems. An unprotected share is one that allows anyone to connect to it.

Unicast is defined as any communication between a single sender and a single receiver over a network. The term exists in contradiction to multicast, communication between a single sender and multiple receivers, and any cast, communication between any sender and the nearest of a group of receivers in a network.

A UDP scan performs scans to determine which UDP ports are open or vulnerable. UDP is a connectionless protocol so there is no equivalent to a TCP syn packet. However, if a UDP packet is sent to a port that is not open, the system will respond with an ICMP port unreachable message.

A virtual private network (VPN) extends a private network across a public network, such as the internet. Vpn enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. A VPN is created by establishing a virtual point-to-point connection through the use of dedicated connections, virtual tunneling protocols, or traffic encryption. For example, if a corporation has lans at several different sites, each connected to the internet by a firewall, the corporation could create a VPN by (a) using encrypted tunnels to connect from firewall to firewall across the internet and (b) not allowing any other traffic through the firewalls. A VPN is generally less expensive to build and operate than a dedicated real network, because the virtual network shares the cost of system resources with other users of the real network.