Glossary

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A

ABI
Application Binary Interface

An ABI is an interface that defines how two modules interact with each other at the machine code level. Most often, these modules are applications using external libraries. An ABI defines a low-level and hardware-dependent interface compared to an API, which is considered high-level and hardware-independent.

ACL
Access Control List

An ACL is a list of access permissions that defines entities and their access rights to resources. ACLs can specify access with varying levels of granularity, ranging from full access to a resource, to permission for a specific operation.

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AD
Active Directory

An AD is a Microsoft service that acts as a central database storing and managing information about network objects (user accounts, groups, computers and shared resources) and their security in a Windows-based network.

ADSys

ADSys is an Ubuntu-specific Active Directory (AD) client developed by Canonical. ADSys complements System Security Services Daemon (SSSD) by adding native Group Policy Object support, privilege management, and custom scripts execution.

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AES
Advanced Encryption Standard

An AES is a symmetric encryption algorithm designed to encrypt data securely into an unreadable format that can only be decrypted with the same key used for encryption.

Related topic(s):

  • Security

Alertmanager

Alertmanager is an open-source monitoring system developed by the Prometheus project to monitor and handle alerts. It offers several key features, including Grouping to combine alerts, Inhibition to suppress certain alerts when others are already firing, and Silencing to temporarily mute specific alerts.

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ALUA
Asymmetric Logical Unit Access

It is a storage concept used in Small Computer System Interface (SCSI) environments, particularly in Multi-Path Input/Output (MPIO) setups for shared storage systems like Storage Area Networks (SANs). ALUA informs a system about which paths to a storage device are optimal and which are non-optimal, enabling it to make smarter decisions about accessing shared disks.

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AMD
Advanced Micro Devices

AMD can refer to:

  • The (AMD) company: semiconductor company that designs computer components

  • An AMD processor: a microprocessor designed and produced by the AMD company

  • All Intel/AMD 64-bit processors: the term “amd64” is commonly used to refer to 64-bit processors due to the company’s role in developing this architecture.

Related topic(s):

  • Networking

AMD-SME
AMD Secure Memory Encryption

AMD-SME is a security technology that transparently encrypts all system memory to protect data at rest. It encrypts the entire memory address space of the system using a key derived from the processor, protecting against physical attacks on memory.

Related topic(s):

  • Cryptography, Security

AMD-SEV
AMD Secure Encrypted Virtualization

AMD-SEV is a security technology that encrypts the memory of virtual machines (guests) independently from the host system. It uses a dedicated memory encryption key for each guest VM, preventing the hypervisor from reading or modifying guest memory. This protects guest confidentiality even when the hypervisor is compromised.

Related topic(s):

  • Cryptography, Security, Virtualization

AMD-SEV-ES
AMD Secure Encrypted Virtualization - Encrypted State

AMD-SEV-ES extends AMD-SEV by encrypting the entire VM state, including CPU register contents, in addition to guest memory. This provides enhanced protection against hypervisor-based attacks by preventing the hypervisor from reading or modifying sensitive VM state during execution.

Related topic(s):

  • Cryptography, Security, Virtualization

AMD-SEV-SNP
AMD Secure Encrypted Virtualization - Secure Nested Paging

AMD-SEV-SNP is an extension of AMD-SEV-ES that adds integrity protection for guest memory using Secure Nested Paging. It prevents the hypervisor from modifying guest memory contents and provides cryptographic attestation of the VM’s launch state, ensuring the integrity and confidentiality of guest data.

Related topic(s):

  • Cryptography, Security, Virtualization

Ansible

Ansible is an open-source IT automation tool developed by Red Hat. It offers several automation features, enabling developers and organizations to automate provisioning, configuration management, and application deployment.

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Related topic(s):

  • Automation

Apache2

A robust, open-source HTTP server software designed for the deployment and delivery of web-based applications and content. Functioning as a request-response service, Apache 2 processes HTTP requests from client applications, facilitating the transmission of static and dynamic web resources. It has a modular architecture, supporting a wide array of extensions, enabling customizable functionality including security protocols (e.g., SSL/TLS), server-side scripting, and content management.

Widely deployed in server environments, Apache 2 is a foundational component of numerous web infrastructure stacks, underpinning a substantial portion of internet-accessible services.

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Related topic(s):

  • Web services

API
Application Programming Interface

An API is a type of software interface that acts as a connection between different software programs, allowing them to communicate and exchange data. APIs exist on multiple layers of abstraction, from low-level APIs closest to system hardware to high-level web APIs that enable clients and remote servers to communicate.

AppArmor

AppArmor is a Linux security module that provides Mandatory Access Control (MAC) for programs. AppArmor restricts what applications can do, even when they are compromised. It enforces a set of security policies (called profiles) that define what files, capabilities, and system resources a given program is allowed to access.

See also:

Related topic(s):

  • Security

Apport

Apport is a debugging tool and crash reporting system used in Ubuntu and Debian-based Linux distributions. It can automatically detect crashes in programs and system services, collect detailed diagnostic data, generate crash reports, and prompt the user to send the report to developers via systems like Launchpad. It is typically disabled by default on production systems because it can expose sensitive information in logs, but is used during development or testing.

See also:

Related topic(s):

  • Debugging

APT
Advanced Package Tool

APT is a package management system used by Debian and Debian-based Linux distributions like Ubuntu. APT helps install, update, upgrade, and remove software packages from the command line.

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armhf
ARM hard-float

armhf is a designation used in Linux distributions to describe a 32-bit variant of the ARM architecture that has hardware-based floating-point support. armhf is typically used for lightweight systems or backward compatibility, especially in embedded environments.

Related topic(s):

  • arm32, arm64

ARP
Address Resolution Protocol

ARP is a network protocol used to map an IP address to a physical machine (MAC address) on a local area network (LAN).

Related topic(s):

  • Networking

ASCII
American Standard Code for Information Interchange

A character encoding standard.

async
asynchronous

A term commonly used in programming to describe operations that take place without blocking the main execution thread. Instead of waiting for a particular operation to finish (such as reading a file or making a network request), “async” programs can keep running other operations in the meantime. These operations are often dispatched to the background, allowing them to run in parallel. If needed, however, the program can still wait for the result of an asynchronous operation.

Related topic(s):

  • Concurrency, parallelism, and threading

attestation

In Confidential or Trusted Computing contexts, attestation refers both to the process of generating verifiable evidence about the trustworthiness of a system, and to the artifact produced by that process (commonly called an attestation report or quote).

  • As a process: A TEE or TPM measures critical system components (firmware, boot chain, enclave/VM code) and cryptographically signs these measurements with keys rooted in hardware trust. The evidence is then checked by a verifier against reference values or policies.

  • As a document: The signed report (attestation) is the concrete proof presented to a verifier. It contains the measurements and cryptographic signatures used to establish trust.

Attestation may be local (between components on the same host) or remote (to an external verifier). It underpins measured boot, secure provisioning, and Confidential Computing workloads.

Authenticator

An authenticator is any system, method, or mechanism used to verify a user’s identity during the authentication process. It can range from something as simple as a password field (e.g., LDAP bind) to more advanced tools like biometric scanners or one-time code generators. Authenticators are essential components of authentication protocols and can be used in both single-factor and multi-factor authentication setups.

Related topic(s):

  • OpenLDAP, authentication

autocommit

autocommit is a database feature that automatically commits every individual SQL statement as soon as it is executed. When autocommit is enabled, every SQL statement is treated as its own transaction and is applied immediately and permanently.

This means it is impossible to undo or roll back a statement executed with autocommit enabled. While autocommit is a common default in many systems, behavior can vary depending on the database or language bindings. For example, in Python’s sqlite3 module, Python 3.12 introduces changes to transaction control, allowing explicit control over autocommit mode.

See also:

Related topic(s):

  • Databases

autodetect

autodetect is the