A P P E N D I X  B



access control list (ACL)

A software authorization mechanism that enables you to control which users have access to a server. Users can define ACL rules that are specific to a particular file or directory, granting or denying access to one or more users or groups.


In networking, a unique code that identifies a node in the network. Names such as “host1.sun.com” are translated to dotted-quad addresses, such as “” by the Domain Name Service (DNS).

address resolution

A means for mapping Internet addresses into physical media access control (MAC) addresses or domain addresses.

Address Resolution Protocol (ARP)

A protocol used to associate an Internet Protocol (IP) address with a network hardware address (MAC address).


The person with full access (root) privileges to the managed host system.


A software process, usually corresponding to a particular local managed host, that carries out manager requests and makes local system and application information available to remote users.


A message or log generated by the collection and analysis of error events. An alert indicates that there is a need to perform some hardware or software corrective action.

Alert Standard Format (ASF)

A preboot or out-of-band platform management specification that enables a device, such as an intelligent Ethernet controller, to autonomously scan ASF-compliant sensors on the motherboard for voltage, temperature, or other excursions and to send Remote Management and Control Protocol (RMCP) alerts according to the Platform Event Trap (PET) specification. ASF was intended primarily for out-of-band management functions for client desktops. ASF is defined by the Distributed Management Task Force (DMTF).


The process that verifies the identity of a user in a communication session, or a device or other entity in a computer system, before that user, device, or other entity can access system resources. Session authentication can work in two directions. A server authenticates a client to make access-control decisions. The client can authenticate the server as well. With Secure Sockets Layer (SSL), the client always authenticates the server.


The process of granting specific access privileges to a user. Authorization is based on authentication and access control.



A measure of the volume of information that can be transmitted over a communication link. Often used to describe the number of bits per second a network can deliver.

baseboard management controller (BMC)

A device used to manage chassis environmental, configuration, and service functions, and receive event data from other parts of the system. It receives data through sensor interfaces and interprets this data by using the sensor data record (SDR) to which it provides an interface. The BMC provides another interface to the system event log (SEL). Typical functions of the BMC are to measure processor temperature, power supply values, and cooling fan status. The BMC can take autonomous action to preserve system integrity.

baud rate

The rate at which information is transmitted between devices, for example, between a terminal and a server.


In the Lightweight Directory Access Protocol (LDAP), this refers to the authentication process that LDAP requires when users access the LDAP directory. Authentication occurs when the LDAP client binds to the LDAP server.

BIOS (Basic Input/Output System)

System software that controls the loading of the operating system and testing of hardware at system power on. BIOS is stored in read-only memory (ROM).

bits per second (bps)

The unit of measurement for data transmission speed.

boot loader

A program contained in read-only memory (ROM) that automatically runs at system power-on to control the first stage of system initialization and hardware tests. The boot loader then transfers control to a more complex program that loads the operating system.



A copy of original data that is stored locally, often with instructions or the most frequently accessed information. Cached data does not have to be retrieved from a remote server again when requested. A cache increases effective memory transfer rates and processor speed.


Public key data assigned by a trusted Certificate Authority (CA) to provide verification of an entity’s identity. This is a digitally signed document. Both clients and servers can have certificates. Also called a “public key certificate.”

Certificate Authority (CA)

A trusted organization that issues public key certificates and provides identification to the owner of the certificate. A public key Certificate Authority issues certificates that state a relationship between an entity named in the certificate, and a public key that belongs to that entity, which is also present in the certificate.

Chassis Monitoring Module (CMM)

A typically redundant, hot-pluggable module that works with the service processor (SP) on each blade to form a complete chassis management system.


In the client/server model, a system or software on a network that remotely accesses resources of a server on a network.

command-line interface (CLI)

A text-based interface that enables users to type executable instructions at a command prompt.



A terminal, or dedicated window on a screen, where system messages are displayed. The console window enables you to configure, monitor, maintain, and troubleshoot many server software components.

Coordinated Universal Time (UTC)

The international standard for time. UTC was formerly called Greenwich Meridian Time (GMT). UTC is used by Network Time Protocol (NTP) servers to synchronize systems and devices on a network.

core file

A file created by the Solaris or Linux operating system when a program malfunctions and terminates. The core file holds a snapshot of memory, taken at the time the fault occurred. Also called a “crash dump file.”

critical event

A system event that seriously impairs service and requires immediate attention.

customer-replaceable unit (CRU)

A system component that the user can replace without special training or tools.


Data Encryption Standard (DES)

A common algorithm for encrypting and decrypting data.

Desktop Management Interface (DMI)

A specification that sets standards for accessing technical support information about computer hardware and software. DMI is hardware and operating system (OS) independent, and can manage workstations, servers, or other computing systems. DMI is defined by the Distributed Management Task Force (DMTF).

digital signature

A certification of the source of digital data. A digital signature is a number derived from a public key cryptographic process. If the data is modified after the signature was created, the signature becomes invalid. For this reason, a digital signature can ensure data integrity and detection of data modification.

Digital Signature Algorithm (DSA)

A cryptographic algorithm specified by the Digital Signature Standard (DSS). DSA is a standard algorithm used to create digital signatures.

direct memory access (DMA)

The transfer of data directly into memory without supervision of the processor.

directory server

In the Lightweight Directory Access Protocol (LDAP), a server which stores and provides information about people and resources within an organization from a logically centralized location.


Distinguished Name (DN)

In the Lightweight Directory Access Protocol (LDAP), a unique text string that identifies an entry’s name and location within the directory. A DN can be a fully qualified domain name (FQDN) that includes the complete path from the root of the tree.

Distributed Management Task Force (DMTF)

A consortium of over 200 companies that authors and promotes standards for the purpose of furthering the ability to remotely manage computer systems. Specifications from the DTMF include the Desktop Management Interface (DMI), the Common Information Model (CIM), and the Alert Standard Format (ASF).


A grouping of hosts that is identified by a name. The hosts usually belong to the same Internet Protocol (IP) network address. The domain also refers to the last part of a fully qualified domain name (FQDN) that identifies the company or organization that owns the domain. For example, “sun.com” identifies Sun Microsystems as the owner of the domain in the FQDN “docs.sun.com.”

domain name

The unique name assigned to a system or group of systems on the Internet. The host names of all the systems in the group have the same domain name suffix, such as “sun.com.” Domain names are interpreted from right to left. For example, “sun.com” is both the domain name of Sun Microsystems, and a subdomain of the top-level “.com” domain.

Domain Name Server (DNS)

The server that typically manages host names in a domain. DNS servers translate host names, such as “www.example.com,” into Internet Protocol (IP) addresses, such as “”

Domain Name System (DNS)

A distributed name resolution system that enables computers to locate other computers on a network or the Internet by domain name. The system associates standard Internet Protocol (IP) addresses, such as “,” with host names, such as “www.sun.com.” Machines typically get this information from a DNS server.

Dynamic Host Configuration Protocol (DHCP)

A protocol that enables a DHCP server to assign Internet Protocol (IP) addresses dynamically to systems on a Transmission Control Protocol/Internet Protocol (TCP/IP) network.


enhanced parallel port (EPP)

A hardware and software standard that enables systems to transmit data at twice the speed of standard parallel ports.


An industry-standard type of local area network (LAN) that enables real-time communication between systems connected directly through cables. Ethernet uses a Carrier Sense Multiple Access/Collision Detection (CSMA/CD) algorithm as its access method, wherein all nodes listen for, and any node can begin transmitting data. If multiple nodes attempt to transmit at the same time (a collision), the transmitting nodes wait for a random time before attempting to transmit again.


A change in the state of a managed object. The event-handling subsystem can provide a notification to which a software system must respond when it occurs, but which the software did not solicit or control.

externally initiated reset (XIR)

A signal that sends a “soft” reset to the processor in a domain. XIR does not reboot the domain. An XIR is generally used to escape from a hung system in order to reach the console prompt. A user can then generate a core dump file, which can be useful in diagnosing the cause of the hung system.



The automatic transfer of a computer service from one system, or more often a subsystem, to another to provide redundant capability.

Fast Ethernet

Ethernet technology that transfers data up to 100M bits per second. Fast Ethernet is backward-compatible with 10M-bit per second Ethernet installations.

field-replaceable unit (FRU)

A system component that is replaceable at the customer site.

file system

A consistent method by which information is organized and stored on physical media. Different operating systems typically have different file systems. File systems are often a tree-structured network of files and directories, with a root directory at the top and parent and child directories below root.

File Transfer Protocol (FTP)

A basic Internet protocol based on Transmission Control Protocol/Internet Protocol (TCP/IP) that enables the retrieving and storing of files between systems on the Internet without regard for the operating systems or architectures of the systems involved in the file transfer.


A network configuration, usually both hardware and software, that protects networked computers within an organization from outside access. A firewall can monitor or prohibit connections to and from specified services or hosts.


Software that is typically used to help with the initial booting stage of a system and with system management. Firmware is embedded in read-only memory (ROM) or programmable ROM (PROM).

fully qualified domain name (FQDN)

The complete and unique Internet name of a system, such as “www.sun.com.” The FQDN includes a host server name (www) and its top-level (.com) and second-level (.sun) domain names. A FQDN can be mapped to a system’s Internet Protocol (IP) address.



A computer or program that interconnects two networks and then passes data packets between the networks. A gateway has more than one network interface.

Gigabit Ethernet

Ethernet technology that transfers data up to 1000M bits per second.

graphical user interface (GUI)

An interface that uses graphics, along with a keyboard and mouse, to provide easy-to-use access to an application.



A system, such as a backend server, with an assigned Internet Protocol (IP) address and host name. The host is accessed by other remote systems on the network.

host ID

Part of the 32-bit Internet Protocol (IP) address used to identify a host on a network.

host name

The name of a particular machine within a domain. Host names always map to a specific Internet Protocol (IP) address.

hot plug

Describes a component that is safe to remove or add while the system is running. However, before removing the component, the system administrator must prepare the system for the hot-plug operation. After the new component is inserted, the system administrator must instruct the system to reconfigure the device into the system.

hot swap

Describes a component that can be installed or removed by simply pulling the component out and putting a new component into a running system. The system either automatically recognizes the component change and configures it or requires user interaction to configure the system. However, in neither case is a reboot required. All hot-swappable components are hot pluggable, but not all hot-pluggable components are hot swappable.

Hypertext Transfer Protocol (HTTP)

The Internet protocol that retrieves hypertext objects from remote hosts. HTTP messages consist of requests from client to server and responses from server to client. HTTP is based on Transmission Control Protocol/Internet Protocol (TCP/IP).

Hypertext Transfer Protocol Secure (HTTPS)

An extension of HTTP that uses Secure Sockets Layer (SSL) to enable secure transmissions over a Transmission Control Protocol/Internet Protocol (TCP/IP) network.


in-band system management

Server management capability that is enabled only when the operating system is initialized and the server is functioning properly.

Integrated Lights Out Manager (ILOM)

An integrated hardware, firmware, and software solution for in-chassis or in-blade system management.

Intelligent Platform Management Interface (IPMI)

A hardware-level interface specification that was designed primarily for out-of-band management of server systems over a number of different physical interconnects. The IPMI specification describes extensive abstractions regarding sensors. This enables a management application running on the operating system (OS) or in a remote system to comprehend the environmental makeup of the system and to register with the system’s IPMI subsystem to receive events. IPMI is compatible with management software from heterogeneous vendors. IPMI functionality includes Field Replacable Unit (FRU) inventory reporting, system monitoring, logging, system recovery (including local and remote system resets and power on and off capabilities), and alerting.

Internet Control Message Protocol (ICMP)

An extension to the Internet Protocol (IP) that provides for routing, reliability, flow control, and sequencing of data. ICMP specifies error and control messages used with the IP.

Internet Protocol (IP)

The basic network layer protocol of the Internet. IP enables the unreliable delivery of individual packets from one host to another. IP does not guarantee that the packet will be delivered, how long it will take, or if multiple packets will be delivered in the order they were sent. Protocols layered on top of IP add connection reliability.

Internet Protocol (IP) address

In Transmission Control Protocol/Internet Protocol (TCP/IP), a unique 32-bit number that identifies each host or other hardware system on a network. The IP address is a set of numbers separated by dots, such as “,” which specifies the actual location of a machine on an intranet or the Internet.


A utility used to manage IPMI-enabled devices. IPMItool can manage IPMI functions of either the local system or a remote system. Functions include managing field-replaceable unit (FRU) information, local area network (LAN) configurations, sensor readings, and remote system power control.


Java(TM) Web Start application

A web application launcher. With Java Web Start, applications are launched by clicking on the web link. If the application is not present on your system, Java Web Start downloads it and caches it onto your system. Once an application is downloaded to its cache, it can be launched from a desktop icon or browser



The core of the operating system (OS) that manages the hardware and provides fundamental services, such as filing and resource allocation, that the hardware does not provide.

Keyboard Controller Style (KCS) interface

A type of interface implemented in legacy personal computer (PC) keyboard controllers. Data is transferred across the KCS interface using a per-byte handshake.

keyboard, video, mouse, storage (KVMS)

A series of interfaces that enables a system to respond to keyboard, video, mouse, and storage events.


lights out management (LOM)

Technology that provides the capability for out-of-band communication with the server even if the operating system is not running. This enables the system administrator to switch the server on and off; view system temperatures, fan speeds, and so forth; and restart the system from a remote location.

Lightweight Directory Access Protocol (LDAP)

A directory service protocol used for the storage, retrieval, and distribution of information, including user profiles, distribution lists, and configuration data. LDAP runs over Transmission Control Protocol/Internet Protocol (TCP/IP) and across multiple platforms.

Lightweight Directory Access Protocol (LDAP) server

A software server that maintains an LDAP directory and service queries to the directory. The Sun Directory Services and the Netscape Directory Services are implementations of an LDAP server.

local area network (LAN)

A group of systems in close proximity that can communicate via connecting hardware and software. Ethernet is the most widely used LAN technology.

local host

The processor or system on which a software application is running.


major event

A system event that impairs service, but not seriously.

Management Information Base (MIB)

A tree-like, hierarchical system for classifying information about resources in a network. The MIB defines the variables that the master Simple Network Management Protocol (SNMP) agent can access. The MIB provides access to the server’s network configuration, status, and statistics. Using SNMP, you can view this information from a network management station (NMS). By industry agreement, individual developers are assigned portions of the tree structure to which they may attach descriptions that are specific to their own devices.

man pages

Online UNIX documentation.

media access control (MAC) address

Worldwide unique, 48-bit, hardware address number that is programmed in to each local area network interface card (NIC) at the time of manufacture.

Message Digest 5 (MD5)

A secure hashing function that converts an arbitrarily long data string into a short digest of data that is unique and of fixed size.

minor event

A system event that does not currently impair service, but which needs correction before it becomes more severe.



In the tree structure of a Lightweight Directory Access Protocol (LDAP) directory, a set of unique names from which an object name is derived and understood. For example, files are named within the file namespace and printers are named within the printer namespace.

Network File System (NFS)

A protocol that enables disparate hardware configurations to function together transparently.

Network Information Service (NIS)

A system of programs and data files that UNIX systems use to collect, collate, and share specific information about machines, users, file systems, and network parameters throughout a network of computer systems.

network interface card (NIC)

An internal circuit board or card that connects a workstation or server to a networked device.

network management station (NMS)

A powerful workstation with one or more network management applications installed. The NMS is used to remotely manage a network.

network mask

A number used by software to separate the local subnet address from the rest of a given Internet Protocol (IP) address.

Network Time Protocol (NTP)

An Internet standard for Transmission Control Protocol/Internet Protocol (TCP/IP) networks. NTP synchronizes the clock times of networked devices with NTP servers to the millisecond using Coordinated Universal Time (UTC).


An addressable point or device on a network. A node can connect a computing system, a terminal, or various peripheral devices to the network.

nonvolatile memory

A type of memory that ensures that data is not lost when system power is off.


object identifier (OID)

A number that identifies an object’s position in a global object registration tree. Each node of the tree is assigned a number, so that an OID is a sequence of numbers. In Internet usage the OID numbers are delimited by dots, for example, “” In the Lightweight Directory Access Protocol (LDAP), OIDs are used to uniquely identify schema elements, including object classes and attribute types.

OpenBoot(TM) PROM

A layer of software that takes control of an initialized system after the power-on self-test (POST) successfully tests components. OpenBoot PROM builds data structures in memory and boots the operating system.


An operating system-independent, event-driven library for simplifying access to the Intelligent Platform Management Interface (IPMI).


A user with limited privileges to the managed host system.

out-of-band (OOB) system management

Server management capability that is enabled when the operating system network drivers or the server are not functioning properly.



A method used by a computer for checking that data received matches data sent. Also refers to information stored with data on a disk that enables the controller to rebuild data after a drive failure.


A set of privileges granted or denied to a user or group that specify read, write, or execution access to a file or directory. For access control, permissions state whether access to the directory information is granted or denied, and the level of access that is granted or denied.

physical address

An actual hardware address that matches a memory location. Programs that refer to virtual addresses are subsequently mapped to physical addresses.

Platform Event Filtering (PEF)

A mechanism that configures the service processor to take selected actions when it receives event messages, for example, powering off or resetting the system or triggering an alert.

Platform Event Trap (PET)

A configured alert triggered by a hardware or firmware (BIOS) event. A PET is an Intelligent Platform Management Interface (IPMI)-specific, Simple Network Management Protocol (SNMP) trap, which operates independently of the operating system.


The location (socket) to which Transmission Control Protocol/Internet Protocol (TCP/IP) connections are made. Web servers traditionally use port 80, the File Transfer Protocol (FTP) uses port 21, and Telnet uses port 23. A port enables a client program to specify a particular server program in a computer on a network. When a server program is started initially, it binds to its designated port number. Any client that wants to use that server must send a request to bind to the designated port number.

port number

A number that specifies an individual Transmission Control Protocol/Internet Protocol (TCP/IP) application on a host machine, providing a destination for transmitted data.

power cycling

The process of turning the power to a system off then on again.

power-on self-test (POST)

A program that takes uninitialized system hardware and probes and tests its components at system startup. POST configures useful components into a coherent, initialized system and hands it over to the OpenBoot PROM. POST passes to OpenBoot PROM a list of only those components that have been successfully tested.

Preboot Execution Environment (PXE)

An industry-standard client/server interface that enables a server to boot an operating system (OS) over a Transmission Control Protocol/Internet Protocol (TCP/IP) network using Dynamic Host Configuration Protocol (DHCP). The PXE specification describes how the network adapter card and BIOS work together to provide basic networking capabilities for the primary bootstrap program, enabling it to perform a secondary bootstrap over the network, such as a TFTP load of an OS image. Thus, the primary bootstrap program, if coded to PXE standards, does not need knowledge of the system’s networking hardware.

Privacy Enhanced Mail (PEM)

A standard for Internet electronic mail that encrypts data to ensure privacy and data integrity.


A set of rules that describes how systems or devices on a network exchange information.


A mechanism whereby one system acts on behalf of another system in responding to protocol requests.

public key encryption

A cryptographic method that uses a two-part key (code) that is made up of public and private components. To encrypt messages, the published public keys of the recipients are used. To decrypt messages, the recipients use their unpublished private keys, which are known only to them. Knowing the public key does not enable users to deduce the corresponding private key.


real-time clock (RTC)

A battery-backed component that maintains the time and date for a system, even when the system is powered off.


An operating system-level operation that performs a system shutdown followed by a system boot. Power is a prerequisite.


The channeling of input or output to a file or device rather than to the standard input or output of a system. The result of redirection sends input or output that a system would normally display to the display of another system.

Remote Management and Control Protocol (RMCP)

A networking protocol that enables an administrator to respond to an alert remotely by powering the system on or off or forcing a reboot.

remote procedure call (RPC)

A method of network programming that enables a client system to call functions on a remote server. The client starts a procedure at the server and the result is transmitted back to the client.

remote system

A system other than the one on which the user is working.


A hardware-level operation that performs a system power-off, followed by a system power-on.


In UNIX operating systems, the name of the superuser (root). The root user has permissions to access any file and carry out other operations not permitted to ordinary users. Roughly equivalent to the Administrator user name on Windows Server operating systems.

root directory

The base directory from which all other directories stem, either directly or indirectly.


A system that assigns a path over which to send network packets or other Internet traffic. Although both hosts and gateways do routing, the term “router” commonly refers to a device that connects two networks.

RSA algorithm

A cryptographic algorithm developed by RSA Data Security, Inc. It can be used for both encryption and digital signatures.


Definitions that describe what type of information can be stored as entries in the directory. When information that does not match the schema is stored in the directory, clients attempting to access the directory might be unable to display the proper results.


Secure Shell (SSH)

A UNIX shell program and network protocol that enables secure and encrypted log in and execution of commands on a remote system over an insecure network.

Secure Sockets Layer (SSL)

A protocol that enables client-to-server communication on a network to be encrypted for privacy. SSL uses a key exchange method to establish an environment in which all data exchanged is encrypted with a cipher and hashed to protect it from eavesdropping and alteration. SSL creates a secure connection between a web server and a web client. Hypertext Transfer Protocol Secure (HTTPS) uses SSL.

sensor data record (SDR)

To facilitate dynamic discovery of features, the Intelligent Platform Management Interface (IPMI) includes this set of records. They include software information, such as how many sensors are present, what type they are, their events, threshold information, and so on. The sensor data records enable software to interpret and present sensor data without any prior knowledge about the platform.

serial console

A terminal or a tip line connected to the serial port on the service processor. A serial console is used to configure the system to perform other administrative tasks.

server certificate

A certificate used with Hypertext Transfer Protocol Secure (HTTPS) to authenticate web applications. The certificate can be self-signed or issued by a Certificate Authority (CA).

Server Message Block (SMB) protocol

A network protocol that enables files and printers to be shared across a network. The SMB protocol provides a method for client applications to read and write to files on and request services from server programs in the network. The SMB protocol enables you to mount file systems between Windows and UNIX systems. The SMB protocol was designed by IBM and subsequently modified by Microsoft Corp. Microsoft renamed the protocol the Common Internet File System (CIFS).

service processor (SP)

A device used to manage chassis environmental, configuration, and service functions, and receive event data from other parts of the system. It receives data through sensor interfaces and interprets this data by using the sensor data record (SDR) to which it provides an interface. The SP provides another interface to the system event log (SEL). Typical functions of the SP are to measure processor temperature, power supply values, and cooling fan status. The SP can take autonomous action to preserve system integrity.

session time-out

A specified duration after which a server can invalidate a user session.

Simple Mail Transfer Protocol (SMTP)

A Transmission Control Protocol/Internet Protocol (TCP/IP) used for sending and receiving email.

Simple Network Management Protocol (SNMP)

A simple protocol used to exchange data about network activity. With SNMP, data travels between a managed device and a network management station (NMS). A managed device can be any device that runs SNMP, such as hosts, routers, web servers, or other servers on the network.


A working scheme that divides a single logical network into smaller physical networks to simplify routing. The subnet is the portion of an Internet Protocol (IP) address that identifies a block of host IDs.

subnet mask

A bit mask used to select bits from an Internet address for subnet addressing. The mask is 32 bits long and selects the network portion of the Internet address and one or more bits of the local portion. Also called an “address mask.”


A special user who has privileges to perform all administrative functions on a UNIX system. Also called “root.”

system event log (SEL)

A log that provides nonvolatile storage for system events that are logged autonomously by the service processor or directly with event messages sent from the host.



The virtual terminal program that enables the user of one host to log in to a remote host. A Telnet user of one host who is logged in to a remote host can interact as a normal terminal user of the remote host.


Minimum and maximum values within a range that sensors use when monitoring temperature, voltage, current, and fan speed.


A specified time after which the server should stop trying to finish a service routine that appears to be hung.

transmission control block (TCB)

Part of the Transmission Control Protocol/Internet Protocol (TCP/IP) that records and maintains information about the state of a connection.

Transmission Control Protocol/Internet Protocol (TCP/IP)

An Internet protocol that provides for the reliable delivery of data streams from one host to another. TCP/IP transfers data between different types of networked systems, such as systems running Solaris, Microsoft Windows, or Linux software. TCP guarantees delivery of data and that packets will be delivered in the same sequence in which they were sent.


Event notification made by Simple Network Management Protocol (SNMP) agents by their own initiative when certain conditions are detected. SNMP formally defines seven types of traps and permits subtypes to be defined.

Trivial File Transport Protocol (TFTP)

A simple transport protocol that transfers files to systems. TFTP uses User Datagram Protocol (UDP).


Universal Serial Bus (USB)

An external bus standard that supports data transfer rates of 450M bits per second (USB 2.0). A USB port connects devices, such as mouse pointers,

user account

A record of essential user information that is stored on the system. Each user who accesses a system has a user account.

User Datagram Protocol (UDP)

A connectionless transport layer protocol that adds some reliability and multiplexing to the Internet Protocol (IP). UDP enables one application program to deliver, via IP, datagrams to another application program on another machine. The Simple Network Management Protocol (SNMP) is usually implemented over UDP.

user identification (userid)

A unique string identifying a user to a system.

user identification number (UID number)

The number assigned to each user accessing a UNIX system. The system uses UID numbers to identify, by number, the owners of files and directories.

user name

A combination of letters, and possibly numbers, that identifies a user to the system.


web server

Software that provides services to access the Internet or an intranet. A web server hosts web sites, provides support for HTTP/HTTPS and other protocols, and executes server-side programs.

wide area network (WAN)

A network consisting of many systems that provides file transfer services. A WAN can cover a large physical area, sometimes worldwide.


X.509 certificate

The most common certificate standard. X.509 certificates are documents containing a public key and associated identity information, digitally signed by a Certificate Authority (CA).

X Window System

A common UNIX window system that enables a workstation or terminal to control multiple sessions simultaneously.