Glossary

We are currently compiling and defining terms for this glossary. If you would like to help, please visit our contributions page for details on how to get involved.

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A – B – C – D – E – F – G – H – I – J – K – L – M – N – O – P – Q – R – S – T – U – V – W – X – Y – Z

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.

See also:

Related topic(s):

AD
Active Directory

Work in Progress

ADSys

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

See also:

Related topic(s):

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.

See also:

Related topic(s):

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.

Related topic(s):

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

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.

See also:

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.

See also:

Related topic(s):

  • Web servers

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.

See also:

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

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

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 ability of a system to automatically detect and configure hardware or settings without user input. In Ubuntu Server and other Linux systems, this is used during boot or installation to identify devices like disks, network interfaces, or keyboard layouts. The kernel, installers, and configuration tools rely on autodetection to simplify setup by loading the right drivers and defaults based on the system’s hardware and environment.

Related topic(s):

  • Kernel modules

autoinstall

Autoinstall is a feature in Ubuntu Desktop and Ubuntu Server that provides fully automated installations using a pre-defined configuration file. This file describes how the system should be installed, including disk partitioning, user accounts, package selection, and network settings.

See also:

Related topic(s):

  • cloud-init

autorid

autorid is a Samba ID mapping backend that automatically assigns UID and GID values to security identifiers (SIDs) when integrating with Active Directory (AD). It ensures consistent and persistent Unix ID mapping without requiring manual configuration for each domain or user/group.

See also:

Related topic(s):

  • Samba, Active Directory

AWS
Amazon Web Services

AWS is a cloud computing platform that offers a wide range of on-demand services such as compute, storage, networking, machine learning, analytics and much more. It allows individuals and companies to run applications without owning physical hardware, to scale resources up or down as needed, and to pay only for what they use.

See also:

Related topic(s):

  • Clouds

B

backend

Work in Progress

Backports

Work in Progress

Backtrace

Work in Progress

BDC
Backup Domain Controller

Work in Progress

bind

Work in Progress

BindDN

Work in Progress

BIOS

Work in Progress

BMC
Baseboard Management Controller

Work in Progress

bootloader

Work in Progress

bootstrap

Work in Progress

btrfs
B-tree File System

Work in Progress

C

CA
Certificate Authority

Work in Progress

CAC
Common Access Card

Work in Progress

CARP
Cache Array Routing Protocol

Work in Progress

CCID
Chip Card Interface Device

Work in Progress

CDB
Command Descriptor Block

Work in Progress

CGNAT
Carrier-Grade Network Address Translation

Work in Progress

CGI
Common Gateway Interface

Work in Progress

checksums

Work in Progress

chrony

Work in Progress

chroot

Work in Progress

CIDR
Classless Inter-Domain Routing

Work in Progress

CIFS
Common Internet File System

Work in Progress

CIS
Center for Internet Security

Work in Progress

CLVM
Clustered Logical Volume Manager

Work in Progress

CMS
Configuration Management System

Work in Progress

CN
Common Name

Work in Progress

colocation

Work in Progress

conffile

Work in Progress

config

Work in Progress

connectionless

Work in Progress

containerization

Work in Progress

CPU
Central Processing Unit

Work in Progress

CRL
Certificate Revocation List

Work in Progress

crypto
cryptographic

Work in Progress

CSR
Certificate Signing Request

Work in Progress

CVE
Common Vulnerabilities and Exposures

Work in Progress

D

DAC
Discretionary access control

A form of access control where the owner of a resource can grant/revoke permissions to other users.

Related topic(s):

  • Security

daemonize

The process of converting a program to run in the background as a service, independent of user sessions.

DARPA
Defense Advanced Research Projects Agency

A research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use in the military.

DASD
Direct Access Storage Device

This term was coined by IBM to refer to a type of storage that allows random access to storage (hard-drives, optical discs, etc). It contrasts with sequential access storage such as magnetic tape or punched cards.

Related topic(s):

  • Storage

Datagram

In networking, a self contained, independent packet sent over a network. It can be routed from source to destination without relying on earlier or subsequent transfers.

Related topic(s):

  • Networking

A connection between two databases (mainly Oracle and PostgreSQL), allowing one database to query data from the other.

Related topic(s):

  • Databases

DC
Domain Component

Work in progress

DDNS
Dynamic Domain Name System

A service that automatically updates DNS records when the underlying IP address changes (aka, dynamic IP).

Related topic(s):

  • Networking

debconf

A configuration management system handling the configuration of software packages during installation or upgrades by prompting users for necessary settings and storing them for subsequent installations or updates.

deduplication

Process of removing duplicate copies of data in storage spaces. The redundant data is then replaced with a reference to the original.

denylist

In cyber-security, a denylist is a list of entities (IP, domains, emails, etc), that are explicitly denied access to a system or service.

Related topic(s):

  • Security

DER
Distinguished Encoding Rules

A standardized encoding format for data (mostly cryptographic certificates and keys) for transmission and storage.

DGC
Distributed Garbage Collection

A process used in distributed systems to manage memory across multiple interconnected computers allowing identification and reclaiming of unused memory across nodes.

DHCP
Dynamic Host Configuration Protocol

A network protocol used to automatically assign network configuration details (IP, DNS, gateway, etc) to devices allowing for easy network management and connections within the network.

DHCPD
Dynamic Host Configuration Protocol Daemon

Server software responsible for assigning the network configuration via DHCP.

DIT
Directory Information Tree

In directory services (LDAP) this is a hierarchical tree-like structure used to organize and store information.

Related topic(s):

  • OpenLDAP

DKMS
Dynamic Kernel Module Support

A framework used in Linux systems to automatically rebuild and install kernel modules when the kernel is updated.

Related topic(s):

  • Kernel

DMA
Direct Memory Access

DMA is a technology that allows peripheral devices (hard drives, network cards, etc) to access the system’s memory directly, bypassing the CPU and thus improving performance.

DMAR
Direct Memory Access Remapping

DMAR is a technology used to control and secure Direct Memory Access operations and ensure that devices can only access memory regions they are authorized to. This helps to prevent unauthorized access, memory corruption, or security vulnerabilities. It is often used in virtualized environments to isolate devices between virtual machines (VMs) and the host system.

dmesg

A command in Linux systems that displays system logs related to hardware, drivers, and kernel events, such as system startup, device detection, and errors. It is commonly used for troubleshooting hardware issues and system diagnostics.

DN
Distinguished Name

In directory services (LDAP), this is a unique identifier used to represent an entry in a directory, such as a user or a group. It’s often composed of sub-components like CN, OU, or DC.

DNS
Domain Name System

A system that translates human-readable domain names (e.g. ubuntu.com) to their IP addresses (185.125.190.20).

Related topic(s):

  • Networking

dnsmasq

A lightweight, open-source DNS and DHCP server software.

DNSSEC
Domain Name System Security Extensions

DNSSEC is a set of security extensions to DNS which allow DNS data to be verified for authenticity and integrity.

Related topic(s):

  • Security

Docker

One of the most popular containerization platforms, which allows developers to package applications – together with their dependencies – into lightweight containers. This provides a consistently reproducible environment for deploying applications.

Related topic(s):

  • Containers

DocumentRoot

A directive in web server configuration files that specifies the directory on the server where web files are stored (root location).

dpkg

dpkg is a package manager for Debian-based systems. It can install, remove, and build packages, but unlike other package management systems, it cannot automatically download and install packages -– or their dependencies.

DRBD
Distributed Replicated Block Device

A software-based storage solution for Linux that allows for the mirroring of block devices between multiple hosts. The replication is transparent to other applications on the host systems. Any block device hard disks, partitions, RAID devices, logical volumes, etc can be mirrored.

Related topic(s):

  • Storage

DTLS
Datagram Transport Layer Security

A protocol that provides security for datagram-based communication, such as UDP. It is designed to offer similar security features as TLS but adapted for the connectionless nature of datagram protocols.

E

EAL
Environment Abstraction Layer

A software layer that provides a standardized interface between an operating system and the underlying hardware. It abstracts hardware-specific details, allowing software to run on different hardware platforms without modification.

ECKD
Extended Count Key Data

A disk storage format used by IBM mainframe systems, which provides advanced features such as better error detection and correction, as well as enhanced management of data records.

EFI
Extensible Firmware Interface

A type of firmware interface designed to initialize hardware and load the operating system during the boot process of a computer. Replacement for the older BIOS and ancestor of the UEFI.

A text-based web browser for Unix-like operating systems. It allows users to browse the web in a terminal, making it ideal for environments without a GUI.

Engenio

A company that developed and manufactured storage systems including SAN and NAS. Later acquired by LSI Corporation and then by Seagate Technology.

EOL
End of life

When a product, service, software is no longer supported or maintained.

ERD
Enterprise Ready Drivers

Drivers that are specifically designed and optimized for use in enterprise environments, where stability, performance, and reliability are critical.

ESM
Expanded Security Maintenance

A service provided by Canonical to extend security updates and patches for older LTS releases of the Ubuntu operating system after the LTS standard support period has ended.

ESXi

A bare-metal virtualization platform created by VMWare that enables multiple virtual machines to operate on a single physical server.

F

failover

In a Storage Area Network (SAN) environment, this occurs when data flows into an alternative I/O path because a cable, switch, or controller in the current path failed.

It is a common feature in high availability environments and is handled (usually automatically) by multipathing software.

fallbacks

This is a manual or automatic switch to an alternative method, when the primary option fails or is less preferred.

FastCGI
Fast Common Gateway Interface

FastCGI is an extension of the CGI protocol that starts a persistent FastCGI application process, allowing it to handle multiple requests instead of starting a new process for each request as a traditional CGI does.

FC
Fiber Channel

FC is a storage networking protocol used for low-latency communication between a storage device and a node in a Storage Area Network (SAN).

FHS
Filesystem Hierarchy Standard

FHS is a standard that defines the directory structure and contents in Linux and Unix-like operating systems.

Fileset

A fileset defines a group of directories that will be included when performing a backup job using Bacula.

Related topic(s):

  • Storage

filesystem

A filesystem defines how data is organized, stored, and accessed on a storage device.

Related topic(s):

  • Storage

Fluentd

Fluentd is a data collection platform that gathers events from a container for later analysis on other platforms.

Related topic(s):

  • Observability, Containers

FQDN
Fully Qualified Domain Name

A FQDN represents a complete name that specifies the exact location of a host within the DNS hierarchy.

Related topic(s):

  • Networking

FreeIPA
Free Identity, Policy, and Audit

FreeIPA is an open-source security solution for Linux/Unix-like systems that stores user identities in an LDAP directory, manages a CA, and enables authentication, policy enforcement, and auditing through integrations with SSSD and Kerberos.

Related topic(s): Security, OpenLDAP

Freenode

Freenode is an open-source Internet Relay Chat (IRC) platform used by many open-source communities for real-time discussions.

frontend

A frontend is a user-friendly interface for managing a complex system.

  • In firewall management, a frontend like ufw simplifies configuring iptables.

  • In QEMU/KVM graphics, a frontend is the virtual graphic adapter presented to the guest OS, allowing it to process and store graphical output in memory. The guest OS treats it like a GPU, while the host determines how to display the output using the backend.

  • In LDAP, the frontend is a unique database that defines global default settings, such as who the admin user is, who can access database entries, or the limit on the number of search results. These settings apply to all LDAP databases inside slapd, unless overridden.

Related topic(s):

  • Virtualization and containers, Security, OpenLDAP.

fsck
File System Check

fsck is a Linux/Unix-like system utility tool that checks for, and repairs, any filesystem errors.

Related topic(s):

  • Storage

FULLTEXT

FULLTEXT is an index type that allows for fast indexing and searching large quantities of text. It takes a sentence, splits it into words, and links them to row IDs. When a search query for a word is made, MySQL quickly looks up the row the word appear in, and retrieves all matching row IDs, rather than scanning the entire table. It can also find similar words using natural language processing.

See also:

Related topic(s):

  • Databases

FW
Firmware

Firmware is a software that runs before an operating system (OS) boots.

  • When a QEMU microvm starts, the firmware initializes minimal virtual hardware like allocating RAM to the OS, and then loads the Linux kernel into memory.

  • In a physical device, firmware configures PCIe devices like GPUs or network cards.

G

gcplogs

A logging driver that allows logs to be forwarded from a Docker container running in Google Cloud to the Google Cloud Logging service.

Related topic(s):

  • Cloud, Containers, Observability

gcrypt

A cryptographic library that supports encryption, hashing, etc. for applications.

Related topic(s):

  • Cryptographic libraries

GDB
GNU Debugger

GDB traces the current execution of a program, with the aim of identifying any issues.

Related topic(s):

  • Debugging

gelf
GELF
Graylog Extended Log Format

GELF is a logging driver that allow logs to be forwarded in JSON format, but with extra unique fields. These logs are sent from a Docker container to a data collector platform like Graylog, Logstash, and Fluentd.

Related topic(s):

  • Containers, Observability

GFS2

A shared-disk filesystem that allows multiple servers to access a single disk. It uses a locking system to ensure that no two servers modify the same data simultaneously, thus preventing data corruption if one server fails. Additionally, fencing is used to isolate failed nodes, ensuring that their locks can be safely recovered.

Related topic(s):

  • High availability, Storage

GB

Gigabyte (unit of measurement) 1 GB = 1024 bytes

GID
Group ID

A GID is an identifier for a collection of users. It helps administrators enforce system or file access permissions on multiple users at once.

Related topic(s):

  • Active Directory integration, Samba, Security, SSSD

gitolite

Gitolite is a tool installed on a central server for managing git repositories and controlling access to them, all via the command line. The central server becomes a git server.

Related topic(s):

  • Backups and version control

GKE
Google Kubernetes Engine

GKE is a managed Kubernetes service provided by Google cloud.

GL
Graphics Library

A GL is an API for interacting with a graphics card, enabling it to perform better rendering.

Related topic(s):

  • Graphics

GNU
GNU’s Not Unix

A recursive acronym, GNU, is an operating system containing several free software packages. It can be used in combination with the Linux kernel.

GnuTLS
GNU’s Not Unix Transport Layer Security

GnuTLS is a GNU software package that secures data-in-transit by implementing the SSL, TLS and DTLS protocol.

Related topic(s):

  • Cryptography, Web services, OpenLDAP

GPG
GNU Privacy Guard

GPG is a GNU software package that secures data-at-rest before sending it to a recepient.

Related topic(s):

  • Security, Cryptography

GPS
Global Positioning System

GPS is a collection of satellites that provides accurate time using radio signals from their atomic clocks. A GPS receiver plugged into a computer can sync with these satellites and generate PPS signal, which delivers ultra-accurate time that applications can use as a time source.

Related topic(s):

  • Networking

GPSD
GPS daemon

This reads data from a GPS receiver and makes it available as a shared resource to multiple applications (e.g., Chrony) to use for precise time synchronization.

Related topic(s):

  • Networking

GPU
Graphics Processing Unit

A GPU enhances graphics rendering for a computer and any virtual machines running inside of it.

Related topic(s):

  • Graphics, Virtualisation and containers

Graylog

A data collector platform for storing, analysing, and interpreting logs. These logs are received from a gelf logging driver in Docker.

Related topic(s):

  • Containers

GPO
Group Policy Object

A set of configuration rules used to manage and enforce security and system behaviours across users or computers within an Active Directory (AD) object.

Related topic(s): Active Directory integration

GSSAPI
Generic Security Services Application Program Interface

GSSAPI is a vendor-agnostic API that uses an existing communication protocol to establish a secure communication between applications. It does this securely by verifying user credentials, ensuring that data being transmitted remains unchanged, preventing unauthorized access, and securely negotiating encryption keys.

Related topic(s):

  • Cryptography

GTK
GIMP Toolkit

GTK is a library used to create graphical user interfaces (GUIs). It provides a visual interface for interacting with the Bacula Director when managing backup-related operations.

Related topic(s):

  • Graphics, Backups and version control

GUI
Graphical User Interface

A GUI is a visual representation of operations within a computer. It is usually represented as icons rather than text only.

GZIP
GNU Zip

GZIP is a GNU software package used to reduce the file size of a backup.

  • When applied directly to files, it replaces the original file type with a .gz type.

  • When used in Bacula’s fileset, it reduces the storage size of backed-up directories within Bacula’s storage volumes.

  • When used to reduce the size of a folder, it works in combination with a tar tool which first combines multiple files into a single archive, before applying GZIP’s size-reduction technique.

Related topic(s):

  • Backups and version control

H

HA
High Availability

HA is the process of ensuring that a system is always up. To achieve this, a redundant system is set up that either takes over when the main system is down or runs alongside the main system to load-balance the workload.

Related topic(s):

  • High availability

HBA
Host Bus Adapter

HBAs are interface cards that connect a server to a storage device.

Related topic(S):

  • Device mapper multipathing

HMAC
Hash-based Message Authentication Code

A HMAC is a type of Message Authentication Code. While a general MAC may use various techniques during combination, HMAC follows a structured way. When a message and its HMAC are sent, the receiver verifies the integrity by computing the HMAC again – if the message is altered, the value will differ.

Related topic(S):

  • Cryptography, Security

HMC
Hardware Management Console

A HMC is used to manage IBM servers. It can handle tasks like configuring network settings, loading Ubuntu installation files and installing the OS.

hostgroup

A group of backend web or database servers with similar configurations.

Related topic(S):

  • Observability

hostname

A hostname identifies a server using a word rather than an IP address. This makes it easier to remember.

HOTP
HMAC-based One-Time Password

HOTP generates a one-time password by using the HMAC algorithm in combination with a counter. When a client presents the OTP, the server compares it with OTPs generated within a specific counter window to find a match.

hotplug

The process of adding or removing a device (USB, disks, etc.) while a virtual machine is running.

HPB
Host Physical Bits

HPB are appended to the name of an Ubuntu machine type. It signifies that a virtual machine will use the same number of bits the host CPU uses to point to physical memory.

HPC
High Performance Computing

HPC is the use of multiple servers to improve the performance of a task.

HSG
High-availability Storage Group

Work in Progress

HSV
Highly-available Storage Virtualization

Work in Progress

HTCP
Hyper Text Caching Protocol

Work in Progress

HTML
HyperText Markup Language

Work in Progress

HTTP
HyperText Transfer Protocol

Work in Progress

HTTPD
HyperText Transfer Protocol Daemon

Work in Progress

HTTPS
HyperText Transfer Protocol Secure

Work in Progress

hugepage

A huge page increases the page size on a host, and as a result, when virtual memory is allocated to an application, there are fewer page table entries required to map the virtual memory to physical memory. The page table entries are stored in Random Access Memory (RAM) and cached in the Translation Lookaside Buffer (TLB).

HWE
Hardware Enablement

Work in Progress

I

ICMP
Internet Control Message Protocol

Work in Progress

ICP
Internet Cache Protocol

Work in Progress

IDENT
Identification Protocol

Work in Progress

IMAP
Internet Messages Access Protocol

Work in Progress

init
initialization

Work in Progress

I/O
Input/Output

Work in Progress

IOMMU
Input-Output Memory Management Unit

Work in Progress

IoT
Internet of Things

Work in Progress

IP
Internet Protocol

Work in Progress

IP address

Work in Progress

IPC
Inter-Process Communication

Work in Progress

IPL
Initial Program Load

Work in Progress

IPMI
Intelligent Platform Management Interface

Work in Progress

IPP
Internet Printing Protocol

Work in Progress

IPSec
Internet Protocol Security

Work in Progress

iptables

Work in Progress

IPVS
IP Virtual Server

Work in Progress

IQN
iSCSI Qualified Name

Work in Progress

IRC
Internet Relay Chat

Work in Progress

ISC
Internet Systems Consortium

Work in Progress

iSCSI
Internet Small Computer System Interface

Work in Progress

ISO
International Organization for Standardization

Work in Progress

ISP
Internet Service Provider

Work in Progress

J

jitter

Jitter is the variation in delay or latency between when data packets are sent and when they are received over a network, causing irregular arrival times at the destination. This variation is often caused by network congestion, packet loss, poor hardware performance or differences in the path packets take.

Related topic(s):

  • Networking

journald

journald, also known as systemd-journald, is a logging service developed by the systemd project as part of the systemd suite. It collects and stores log messages from various sources, including systemd services, kernel messages, system logs, and application logs. journald stores logs in a binary format offering advantages, such as storage efficiency, searchability, and most especially structured logging. In containerized systems like Docker, it functions as a logging driver for containers.

See also:

Related topic(s):

  • Logging, Observability

JSON
JavaScript Object Notation

This is a language-independent text format that uses conventions familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. Due to its simplicity, it is an ideal lightweight data interchange language.

See also:

K

KDC
Key Distribution Center

Work in Progress

keepalive

Work in Progress

Kerberos

Work in Progress

keypair

Work in Progress

keyring

Work in Progress

keysalt

Work in Progress

keyservers

Work in Progress

keytab

Work in Progress

Keytool

Work in Progress

KVM
Kernel-based Virtual Machine

Work in Progress

L

LAN
Local Area Network

Work in Progress

LDAP
Lightweight Directory Access Protocol

Work in Progress

LDIF
LDAP Data Interchange Format

Work in Progress

lightervisor

Work in Progress

Load-balancing

Work in Progress

localhost

Work in Progress

Logfiles

Work in Progress

Logstash

Work in Progress

Logwatch

Work in Progress

LPAR
Logical Partition

Work in Progress

LSI
Logic Systems Incorporated

Work in Progress

LTS
Long-Term Support

Work in Progress

LU
Logical Unit

Work in Progress

LUA
Lua Scripting Language

Work in Progress

LUN
Logical Unit Number

Work in Progress

LV
Logical Volume

Work in Progress

LVM
Logical Volume Manager

Work in Progress

LXC
Linux Containers

Work in Progress

LXD
Linux Container Daemon

Work in Progress

M

MAAS
Metal as a Service

Work in Progress

MAC
Message Authentication Code

A MAC verifies that a message hasn’t been modified during transmission by combining a shared secret key between the sender and receiver, and a hash function.

MAC address

Work in Progress

manpage
manual page

Work in Progress

MCE
Machine Check Exception

Work in Progress

MDA
Mail Delivery Agent

Work in Progress

mdev
Minimal Device Manager

Work in Progress

metapackage

Work in Progress

METAR
Meteorological Aerodrome Report

Work in Progress

microservices

Work in Progress

microVMs

Work in Progress

MOTD
Message of the Day

Work in Progress

mountpoints

Work in Progress

MPIO
Multipath Input/Output

Work in Progress

MSA
Modular Smart Array

Work in Progress

MTA
Mail Transfer Agent

Work in Progress

MTU
Maximum Transmission Unit

Work in Progress

MUA
Mail User Agent

Work in Progress

Multipass

Work in Progress

Multipath

Work in Progress

Multiview

Work in Progress

MySQL

Work in Progress

N

nameserver

Work in Progress

namespace

Work in Progress

NAS
Network Attached Storage

Work in Progress

NAT
Network Address Translation

Work in Progress

Netboot

Work in Progress

Netfilter

Work in Progress

Netplan

Work in Progress

NFS
Network File System

Work in Progress

NFV
Network Functions Virtualization

Work in Progress

nginx

Work in Progress

NIC
Network Interface Card

Work in Progress

NIS
Network Information Service

Work in Progress

NMI
Non-Maskable Interrupt

Work in Progress

NRPE
Nagios Remote Plugin Executor

Work in Progress

NSCQ
Network System Configuration Queue

Work in Progress

NSS
Name Service Switch

Work in Progress

NTP
Network Time Protocol

Work in Progress

NTS
Network Time Security

Work in Progress

NUMA
Non-Uniform Memory Access

Work in Progress

Nvidia

Work in Progress

NVMe
Non-Volatile Memory Express

Work in Progress

NVRAM
Non-Volative Random Access Memory

Work in Progress

NVSwitch

Work in Progress

O

OCF
Open Cluster Framework

Work in Progress

OCFS
Oracle Cluster File System

Work in Progress

OCI
Open Container Initiative

Work in Progress

OCSP
Online Certificate Status Protocol

Work in Progress

OpenLDAP

Work in Progress

OpenSC
Open Smart Card

Work in Progress

OpenSSH

Work in Progress

OpenSSL

Work in Progress

OpenStack

Work in Progress

OpenSUSE

Work in Progress

OpenVPN

Work in Progress

OpenVZ

Work in Progress

OpenWRT

Work in Progress

OS
Operating System

Work in Progress

OSA
Open Systems Adapter

Work in Progress

OSI
Open Systems Interconnection

Work in Progress

OTE
Operational Test and Evaluation

Work in Progress

OTP
One-Time Password

Work in Progress

OU
Organisational Unit

Work in Progress

OverlayFS

Work in Progress

OVS
Open vSwitch

Work in Progress

P

PAM
Pluggable Authentication Module

Work in Progress

passthrough

Work in Progress

PB

Petabyte (unit of measurement) 1 PB = 1024 TB

PCI
Peripheral Component Interconnect

Work in Progress

PCIe
Peripheral Component Interconnect Express

Work in Progress

PCS
Pacemaker/Corosync Stack

Work in Progress

PDC
Primary Domain Controller

Work in Progress

PEM
Privacy Enhanced Mail

Work in Progress

Petitboot

Work in Progress

PgSQL

Work in Progress

PHP
PHP: HyperText Preprocessor

Work in Progress

PID
Process Identifier

Work in Progress

pingable

Work in Progress

PIV
Personal Identity Verification

Work in Progress

PKCS
Public-Key Cryptography Standards

Work in Progress

PKI
Public Key Infrastructure

Work in Progress

pluggable

Work in Progress

PMD
Poll Mode Driver

Work in Progress

POSIX
Portable Operating System Interface (for UNIX)

Work in Progress

Postcopy

Work in Progress

Postfix

Work in Progress

Postgres
PostgreSQL

Work in Progress

PostScript

Work in Progress

PowerShell

Work in Progress

PPA
Personal Package Archive

Work in Progress

ppc
PowerPC

Work in Progress

PPD
PostScript Printer Description

Work in Progress

PPS
Pulse Per Second

Work in Progress

Preboot

Work in Progress

preseed

Work in Progress

Prometheus

Work in Progress

proxy

Work in Progress

PTP
Precision Time Protocol

Work in Progress

PTR
Pointer Record

Work in Progress

PXE
Preboot Execution Environment

Work in Progress

PXELINUX
PXE Linux Loader

Work in Progress

Q

QA
Quality Assurance

Work in Progress

qdevice
Quorum Device

Work in Progress

QEMU
Quick Emulator

Work in Progress

qeth
QDIO Ethernet

Work in Progress

quickstart

Work in Progress

R

RAM
Random Access Memory

Work in Progress

rangesize

Work in Progress

rclone

Work in Progress

RDAC
Redundant Disk Array Controller

Work in Progress

RDBMS
Relational Database Management System

Work in Progress

RDN
Relative Distinguished Name

Work in Progress

Redbook

Work in Progress

renderer

Work in Progress

REXX
Restructured Extended Executor

Work in Progress

RFC
Request For Comments

Work in Progress

rid
Relative Identifier

Work in Progress

RISC-V
Reduced Instruction Set Computing - Version Five

Work in Progress

Rocks

Work in Progress

ROM
Read-Only Memory

Work in Progress

rootDN
Root Distinguished Name

Work in Progress

rootfs
Root File System

Work in Progress

routable

Work in Progress

RSA
Rivest–Shamir–Adleman

RSA is an asymmetric encryption algorithm Work in Progress

rsnapshot

Work in Progress

rsync

Work in Progress

rsyslog

Work in Progress

RTC
Real-Time Clock

Work in Progress

runtime

Work in Progress

S

SAN
Storage Area Network

Work in Progress

sandboxed

Work in Progress

SANLOCK
SAN Locking Daemon

Work in Progress

SASL
Simple Authentication and Security Layer

Work in Progress

SBD
Storage-Based Death

Work in Progress

sbin
System Binaries

Work in Progress

schemas

Work in Progress

SCP
Secure Copy Protocol

Work in Progress

Scrollback

Work in Progress

SCSI
Small Computer System Interface

Work in Progress

SDN
Software-Defined Networking

Work in Progress

sdx
SCSI Desk (x)

Work in Progress

seccomp
Secure computing mode

Work in Progress

SFTP
SSH File Transfer Protocol

Work in Progress

SGI
Silicon Graphics Inc.

Work in Progress

SHA
Secure Hash Algorithm

Work in Progress

sharding

Work in Progress

Shell

Work in Progress

SHM
Shared Memory

Work in Progress

Shorewall
Shoreline Firewall

Work in Progress

SIDs
Security Identifiers

Work in Progress

SIMD
Single Instruction, Multiple Data

Work in Progress

slapd
Standalone LDAP Daemon

Work in Progress

smartcard

Work in Progress

SMB
Server Message Block

Work in Progress

SMS
Short Message Service

Work in Progress

SMTP
Simple Mail Transfer Protocol

Work in Progress

SMTPS
SMTP Secure

Work in Progress

Snap

Work in Progress

snapd

Work in Progress

snapshot

Work in Progress

Snapstore

Work in Progress

SNMP
Simple Network Management Protocol

Work in Progress

SOA
Start of Authority

Work in Progress

Solaris

Work in Progress

SPC
SCSI Primary Commands

Work in Progress

Splunk

Work in Progress

SRU
Stable Release Update

Work in Progress

SSD
Solid State Drive

Work in Progress

SSH
Secure Shell

Work in Progress

SSI
Server-Side Includes

Work in Progress

SSL
Secure Sockets Layer

Work in Progress

SSO
Single Sign-On

Work in Progress

SSSD
System Security Services Daemon

Work in Progress

stateful

Work in Progress

STDIN
Standard Input

Work in Progress

STDOUT
Standard Output

Work in Progress

STDERR
Standard Error

Work in Progress

STK
Storake Tek

Work in Progress

storage

Work in Progress

subcommand

Work in Progress

Subiquity

Work in Progress

subnet
subnetwork

Work in Progress

substring

Work in Progress

subvolume

Work in Progress

sudo
superuser do

Work in Progress

superblock

Work in Progress

Work in Progress

syslog

Work in Progress

systemctl

Work in Progress

Systemd

Work in Progress

T

tasksel
Task selector

Work in Progress

TB

Terabyte (unit of measurement) 1 TB = 1024 GB

TCP
Transmission Control Protocol

Work in Progress

TFTP
Trivial File Transfer Protocol

Work in Progress

TGS
Ticket Granting Service

Work in Progress

TGT
Ticket Granting Ticket

Work in Progress

timedatectl

Work in Progress

timesyncd

Work in Progress

TLB
Translation Lookaside Buffer

TLB is a CPU cache that stores recent page table entries. When the CPU translates a virtual address, it first checks the TLB. If the mapping is found, the translation is fast. If it’s missing, the CPU retrieves the mapping from the page table in memory, which takes longer.

TLS
Transport Layer Security

Work in Progress

tmpfs
Temporary Filesystem

Work in Progress

tmux
Terminal Multiplexer

Work in Progress

topologies

Work in Progress

TOTP
Time-based One-Time Password

Work in Progress

traceback

Work in Progress

Traceroute

Work in Progress

ttys
Teletype Terminals

Work in Progress

TXT
Trusted Execution Technology

Work in Progress

U

UDA
Unified Data Architecture

Work in Progress

UDP
User Datagram Protocol

Work in Progress

UEFI
Unified Extensible Firmware Interface

Work in Progress

ufw
Uncomplicated Firewall

Work in Progress

UID
User Identifier

Work in Progress

UI
User Interface

Work in Progress

unicast

One-to-one communication

unmount

Work in Progress

untrusted

Work in Progress

uptime

Work in Progress

URI
Uniform Resource Identifier

Work in Progress

userspace

Work in Progress

USN
Update Sequence Number

Work in Progress

usr

Refers to the /usr/ directory and stands for “Unix System Resources”

UUIDs
Universally Unique Identifiers

Work in Progress

V

vCPU
Virtual CPU

Work in Progress

VCS
Version Control System

Work in Progress

veth
Virtual Ethernet

Work in Progress

VFIO
Virtual Function I/O

Work in Progress

VFS
Virtual File System

Work in Progress

VFs
Virtual Functions

Work in Progress

VG
Volume Group

Work in Progress

vGPU
Virtual GPU

Work in Progress

virsh
Virtual Shell

Work in Progress

VirtIO
Virtual I/O

Work in Progress

virtual

Work in Progress

virtualization

Work in Progress

VLAN
Virtual Local Area Network

Work in Progress

VM
Virtual Machine

Work in Progress

VNC
Virtual Network Computing

Work in Progress

VPN
Virtual Private Network

Work in Progress

VRRP
Virtual Router Redundancy Protocol

Work in Progress

vsftpd
Very Secure FTP Daemon

Work in Progress

W

WAL
Write-Ahead Logging

Work in Progress

WAN
Wide Area Network

Work in Progress

WCCP
Web Cache Communication Protocol

Work in Progress

Webserver

Work in Progress

winbind
Windows Bind

Work in Progress

WireGuard

Work in Progress

WLAN
Wireless Local Area Network

Work in Progress

WSGI
Web Server Gateway Interface

Work in Progress

WWID
World Wide Identifier

Work in Progress

X

xhtml
Extensible HyperText Markup Language

Work in Progress

XML
Extensible Markup Language

Work in Progress

Y

YAML
YAML Ain’t Markup Language

Work in Progress

Yubikey

Work in Progress

Z

zFCP
zSeries Fibre Channel Protocol

Work in Progress

ZFS
Zettabyte File System

Work in Progress

zpool
ZFS Pool

Work in Progress