Glossary

agent

A software program, typically run on a managed device, that implements the SNMP protocol and services the requests of a manager. Agents can act as proxies for some non-SNMP manageable network nodes.

Agent Extensibility Protocol (AgentX)

A protocol that enables communication between a master SNMP agent and subagents.

ASN.1

Abstract Syntax Notation One. A specification that is used to encode information between a manager and agents in a manner that is independent of the machine and network type.

configuration tokens

Variables that are used for configuring the SNMP agent or modules. Values of tokens can be identifiers, keywords, constants, punctuation, or white space.

context

A collection of managed objects accessible by an SNMP entity. The name for a subset of managed objects.

DAQ

data acquisition. The process of collecting information from a device.

DES

Data Encryption Standard, a standard encryption algorithm used for securing data.

extension

Code that increases the functionality of the SNMP agent. An extension might also be referred to as a MIB module, an extension module, or simply a module.

legacy subagent

A subagent that does not use the AgentX protocol and requires the use of a proxy to communicate with the Net-SNMP agent.

Management Information Base (MIB)

A virtual information store for managed objects. MIBs define the properties of a device that can be managed.

manager

A client application that accesses data from a managed device or system.

master agent

An agent running on a designated SNMP port. The master agent receives SNMP requests from management applications, dispatches the requests to the appropriate subagents, and sends data returned by the subagents to the requester. In addition, the subagents can send traps to the master agent, which are then forwarded to the management application.

MD5

The message digest algorithm, defined in RFC 1321, which converts a message of arbitrary length into a unique 128–bit string. The MD5 algorithm is used to create digital signatures which can be used to verify data integrity.

MIB

Management Information Base.

MIB II

A standard that defines the Management Information Base objects in TCP/IP-based networks that can be managed. MIB II is defined in RFC 1213.

module

Code that increases the functionality of the SNMP agent. A module might also be referred to as a MIB module, an extension module, or an extension.

Net-SNMP

An SNMP agent that is developed as an open source community project. The System Management Agent is based on the Net-SNMP agent.

Network Management Station (NMS)

An application that is used to manage and monitor network devices. The NMS makes SNMP requests to the SNMP agent and receives information from the agent. An NMS is sometimes called a manager or a management application.

Object Identifier (OID)

A sequence of numbers that uniquely identifies each object in a MIB. The OID is a series of integers separated by periods, which indicate the object's place in the MIB tree. For example, the sequence 1.3.6.1.2.1.1.1.0 specifies the system description within the system group of the management subtree.

PDU

Protocol Data Unit. A message, or packet of data, that is transported through network protocol layers. Each layer attaches headers to the packet before passing it along to the next layer. The entire packet, including the user data and headers, is the PDU. SNMP messages consist of a version identifier, an SNMP community name, and a PDU. The PDU types supported in SNMP are GetRequest, GetNextRequest, GetResponse, SetRequest, and Trap.

proxy agent

An agent that acts on behalf of a non-SNMP (foreign) network device. The management station contacts the proxy agent and indicates the identity of the foreign device. The proxy agent translates the protocol interactions it receives from the management station into the interactions supported by the foreign device.

SHA–1

Secure Hash Algorithm - Version 1.0, defined in RFC 3174. SHA is a cryptographic message digest algorithm. The algorithm converts a message into a 160–bit string.

Simple Network Management Protocol (SNMP)

A standard protocol used to manage nodes in the Internet community.

Structure of Management Information (SMI)

An industry-accepted method of organizing object names so that logical access can occur. The SMI states that each managed object must have a name, a syntax, and an encoding. The name, an object identifier (OID), uniquely identifies the object. The syntax defines the data type, such as an integer or a string of octets. The encoding describes how the information associated with the managed objects is serialized for transmission between machines.

subagent

An agent that interacts with a master agent.

trap

A message, sent to a manager, that describes exceptions that occurred on a managed device.

USM

User-based Security Model. A standard for providing SNMP message-level security, described in RFC 3414 at http://www.ietf.org/rfc/rfc3414.txt. This RFC document also includes a MIB for remotely monitoring and managing the configuration parameters for the User-based Security Model.

VACM

View-Based Access Control Mechanism A standard for controlling access to management information, described in RFC 3415 at http://www.ietf.org/rfc/rfc3415.txt. This RFC document also includes a MIB for remotely managing the configuration parameters for the View-based Access Control Model.