The position of a user in relation to a computer system, with which access and action permissions are defined. The user accesses his account with the login.

Open Source software with WEB server function available for UNIX, Linux, Windows and other operating systems. Many Internet Web servers are Apache.

(Address resolution Protocol). Protocol that in a local network associates an IP address to a physical machine, identified by a MAC address.

(Advanced Research Project Agency NETwork). Computer network created in the 1960s by the ARPA agency of the US Department of Defense. It is not used anymore, but the modern internet comes from that technological base.

(American Standard Code for Information Interschange). Code created by the American National Standards Institute to allow communication between computer systems. The standard ASCII characters, including letters, numbers and punctuation marks are 128 and are encoded with 7 bits. The extended version consists of 256 characters encoded with 8 bits.

Not documented way of access left in an application by its programmer, to access it secretly.

Operation consisting of copying important files (documents, configurations) onto a medium, in order to restore the system and not to lose data in the event of theft, damage or malfunction of the computer.

(Basic Input / Output System). Programme resident in the hardware which, at power-up, performs the first system start-up operations (bootstrap). It can be configured with a callable utility by pressing a key when the computer is turned on (usually DEL key).

The minimum unit of information manageable by a digital system. It can be worth 0 or 1 (binary) and is symbolized by the small letter ‘b’.

Software installed in the MBR of the hard disk in order to start an operating system among those present in the system, passing on any configuration parameters. Examples in GNU / Linux are LILO and GRUB.

Sequence of operations initiated by the BIOS that allows a computer to boot.

Set of computers infected by malicious software that put them under the control of criminal groups without users’ knowledge. They are mainly used for sending spam and DDoS threats.

The language with which most software is written, including almost all GNU / Linux.

(Common Gateway Interface). Standard for interfacing application programmes (e.g. databases) with web servers. It allows to provide the user with dynamic web pages (i.e. created in real time) according to the connected application.

application that allows the user to access the services offered by a server. An example of client is the web browser.

Operation with which a source code is translated into an executable one. It is performed by a software called compiler and is specific to the type of processor and operating system on which the generated file will be used.

Small amount of data that a web server can write to the user’s client computer, usually in order to recognize it during a later visit. The risk for users’ privacy is given by the fact that it is possible, through specially prepared websites, to use cookies to track visits from multiple sites to outline users’ interests.

Ironic term used to indicate the GPL license or similar, which in addition to protecting copyright, it paradoxically protects also the freedom of use and dissemination of information.

The Central Processing Unit of a computer.

Technique that allows to hide (crypto = hidden) data, altering them so that only the recipient who has a ‘decryption key’ can read them. We talk about symmetric cryptography when the encryption and decoding keys are the same, while the asymmetric (or double-key) cryptography occurs when the two keys differ, even if they are linked.

(Cascade Style Sheet). Language that defines the formatting, i.e. the ‘visual’ aspect, of an HTML web page.

(Common Unix Printing System). Unified system for managing local and network printers, available on Unix systems.

Set of information structured in a way that makes them accessible to the machine. Traditionally, data are organized in tabular form, with rows called ‘records’ and columns called ‘fields’.

(Distribuited Denial of Service). Cyber-attack technique in which many computers, often belonging to botnets, flood a victim server with connection requests, running out of resources and temporarily putting it out of use.

(Dynamic Host Configuration Protocol). Protocol created to automatically assign an IP address to a client computer, allowing the operating system to be loaded from a server.

File containing a cryptographic key necessary to decode data, web pages, e-mails etc., associated with the identification data of the holder. It is issued by a special certification body, which guarantees the identity of the owner, the scope of use and the period of validity of the key.

Domain Name service that translates mnemonic addresses ( into the corresponding IP address of the host on the Internet. The service is generally given by your provider.

Disk Operating System: Microsoft operating system born in the 80s for the first Personal Computers. It has a character interface, like the Linux console.

(Digital Rights Management). Set of technologies aimed at controlling and protecting copyright in digital media (limitation of usability and copying, identification, tracking). Some of these techniques are considered too invasive and detrimental to individual freedom.

The action of accessing a machine by exploiting a bug in an application or in the operating system.

Two types of file systems used in Linux. For each file, different information is stored, including: the owner, the group to which they belong, reading, writing and execution permissions. EXT3 is called “journalized”, as it keeps track of file editing operations to preserve data integrity in the event of accidental computer shutdown.

Structure with which the operating system stores the files on memory units. In Linux it is represented as a tree structure with the root directory at the base containing other directories, which in turn may contain other ones for different levels.

Hardware or software that controls and filters data traffic between a network or a host and the rest of the Internet, in order to prevent unauthorized access and / or any abuse.

Procedure that organizes the magnetic surface of a disk in a logical structure of tracks and sectors. To be able to accept data, it is then necessary to create a filesystem in the unit (EXT, DOS, NTFS etc.). When referring to hard disks, the term is often used improperly to indicate the simple creation of the filesystem; formatting is generally performed only once during manufacture.

File Transfer Protocol used on TCP / IP computer networks to take files from a host server using a client application.

Mathematical function (the result is also called a hash) which generates a unique string of fixed length starting from a file. The process is not invertible, i.e. it is not possible to reconstruct the file from the result. The hash represents a ‘fingerprint’ of the file, with which it is possible to verify its integrity at any time.

(Or simply Home). In UNIX and GNU / Linux the reserved and binding directory for a user registered in the system. Within his directory the user has full access, but normally he cannot act in the home of other users and in the higher directories. Generally, the home has the name of the corresponding user and is placed in a branch of the filesystem called “/ home”. The path to the Home directory can be indicated with the tilde character: ~.

(Hyper Text Markup Language). The language with which the web pages are coded. It is interpreted by the browser.

(Hyper Text Transfer Protocol). The protocol used for transferring files on the web (HTML pages, images, sounds, etc.).

(Internet Control Message Protocol). The protocol used to convey service information (errors, tests) necessary for the internet functioning.

(Internet Messaging Access Protocol). The most flexible POP email management protocol. For example, it allows you to view the list of messages without downloading them to the client computer.

A connecting element between two entities, or between an entity and the user. It can be physical, for example the keyboard, the network interface, the USB interface, or a concept: the graphic interface, the character interface.

Internet basic Protocol. Each host is characterized by an IP address, consisting of 4 bytes (in version 4 of the protocol: IPv4), often displayed in the form of four digits between 0 and 255 separated by dots (e.g. The public allocation of the addresses is managed by the Internet Assigned Number Authority ( The Ipv6 version, still not so widespread, uses six bytes to extend the number of addressable hosts.

Programming language conceived by Sun Microsystems, also used to include programmes within the web pages.

Interpreted language, completely independent from JAVA, inserted in HTML pages to create dynamic elements.

File in which events or system messages are recorded in chronological order, simplifying the resolution of any problems and keeping track of the performed activities.

(New Network Transfer Protocol). Transfer protocol for Usenet newsgroup messages.

(New Technology File System). Proprietary filesystem developed by Microsoft in the 1990s for the MS Windows NT operating system, now used also in XP.

A set of rules that the hardware and software systems must respect to be able to communicate with each other. E.g. the TCP / IP protocol, the USB, the HTML etc.

Company which provides Internet connection and / or other IT services.

Intellectual product (text, image, film, software, etc.) on which there is no copyright holder. This can be due to expiration, 70 years after the death of the author of the work, or due to explicit renunciation of the rights by the author or in some cases by the law, as in the case of material published by the US government.

Also called bitmap, the representation modality of images through the set of minimal points that compose them, called Pixels. This type of image cannot be enlarged without losing in definition, unlike vector images.

A programme written in a language that does not need to be compiled but is executed directly by a special application, called “interpreter”. Some scripting languages ​​are Bash commands, Perl, JavaScript, Visual Basic etc.

The code in humanly understandable form with which a software is written and which is then compiled to be executed by the machine.

(Structured Query Language). Standard language for creating, accessing and querying databases.

(Secure Sockets Layer). Protocol for a secure communication between client and web server. It uses advanced encryption techniques to avoid the interception of data by an intermediate host.

(Transfert Control Protocol / Internet Protocol). Communication protocol that can be used on computer networks, characterized by sending data in discrete units called packets and by identifying the hosts through the IP address. It is the Internet standard.

(Uniform Resource Identifier). System for identifying a service on a host in mnemonic form, including the name of the service (http: //, ftp: //), the address of the host (, the path on the host and eventually the port.

A memory location used to temporarily store part of the data being processed. In programming languages ​​it is symbolized with a name, sometimes preceded by symbols such as $, % etc.

(Virtual Network Computing). System that allows you to interact with a remote computer, seeing the desktop as if you had it in front of you. It is useful for remote administration and remote assistance functions.

(Virtual Private Network). Connection protocol between corporate computer networks through the Internet using a secure and confidential channel.

(Cross Side Scripting). Exploit technique aimed at websites and carried out by sending special input strings to the server generated with special scripts executed by the browser. It is so named because the page containing the script is generally located on a different site from the one to be attacked.

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