The Simple Network Management Protocol (SNMP) forms part of the internet protocol suite as defined by the Internet Engineering Task Force (IETF). SNMP is used in network management systems to monitor network-attached devices for conditions that warrant administrative attention. It consists of a set of standards for network management, including an Application Layer protocol, a database schema, and a set of data objects.^[1] In computing and telecommunications, the transport layer is the second highest layer in the four and five layer TCP/IP reference models, where it responds to service requests from the application layer and issues service requests to the Internet layer. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. ... The Datagram Congestion Control Protocol (DCCP) is a message-oriented transport layer protocol that is currently under development in the IETF. Applications that might make use of DCCP include those with timingconstraints on the delivery of data such that reliable in-order delivery, when combined with congestion control, is likely... In the field of computer networking, the IETF Signaling Transport (SIGTRAN) working group defined the Stream Control Transmission Protocol (SCTP) as a transport layer protocol in 2000. ... The Resource ReSerVation Protocol (RSVP), described in RFC 2205, is a Transport layer protocol designed to reserve resources across a network for an integrated services Internet. ... The network layer is third layer out of seven in OSI model and it is the third layer out of five in TCP/IP model. ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... Internet Protocol version 4 is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed. ... Internet Protocol version 6 (IPv6) is a network layer protocol for packet-switched internetworks. ... The Open Shortest Path First (OSPF) protocol is a hierarchical interior gateway protocol (IGP) for routing in Internet Protocol, using a link-state in the individual areas that make up the hierarchy. ... Is Is is Yeah Yeah Yeahs third EP, to be released on July 24, 2007. ... The Border Gateway Protocol (BGP) is the core routing protocol of the Internet. ... IPsec (IP security) is a suite of protocols for securing Internet Protocol (IP) communications by authenticating and/or encrypting each IP packet in a data stream. ... In computer networking, the Address Resolution Protocol (ARP) is the standard method for finding a hosts hardware address when only its network layer address is known. ... Reverse Address Resolution Protocol (RARP) is a network layer protocol used to obtain an IP address for a given hardware address (such as an Ethernet address). ... This article is chiefly about the Routing Information Protocol (RIP) for the Internet Protocol, but also discusses some other routing information protocols. ... The Internet Control Message Protocol (ICMP) is one of the core protocols of the Internet protocol suite. ... The ICMP for IPv6 (Internet Control Message Protocol Version 6) is an integral part of the IPv6 architecture and must be completely supported by all IPv6 implementations. ... The Internet Group Management Protocol (IGMP) is a communications protocol used to manage the membership of Internet Protocol multicast groups. ... This article does not cite any references or sources. ... IEEE 802. ... The IEEE 802. ... Official Wi-Fi logo Wi-Fi (pronounced wye-fye, IPA: ) is a wireless technology brand owned by the Wi-Fi Alliance intended to improve the interoperability of wireless local area network products based on the IEEE 802. ... Official WiMax logo WiMAX, the Worldwide Interoperability for Microwave Access, is a telecommunications technology aimed at providing wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access. ... Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells. ... Dynamic synchronous Transfer Mode , or DTM for short, is a network protocol. ... Token-Ring local area network (LAN) technology was developed and promoted by IBM in the early 1980s and standardised as IEEE 802. ... Ethernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs). ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ... In the context of computer networking, frame relay consists of an efficient data transmission technique used to send digital information quickly and cheaply in a relay of frames to one or many destinations from one or many end-points. ... General Packet Radio Service (GPRS) is a Mobile Data Service available to users of Global System for Mobile Communications (GSM) and IS-136 mobile phones. ... Evolution-Data Optimized or Evolution-Data only, abbreviated as EV-DO or EVDO and often EV, is one telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. ... High-Speed Packet Access (HSPA) is a collection of mobile telephony protocols that extend and improve the performance of existing UMTS protocols. ... High-Level Data Link Control (HDLC) is a bit-oriented synchronous data link layer protocol developed by the International Organization for Standardization (ISO). ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... The Point-to-Point Tunneling Protocol (PPTP) is a method for implementing virtual private networks. ... In computer networking, the Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs). ... ISDN redirects here. ... ARCNET (also CamelCased as ARCnet, an acronym from Attached Resource Computer NETwork) is a local area network (LAN) protocol, similar in purpose to Ethernet or Token Ring. ... This article does not cite any references or sources. ... IEEE photograph of a diagram with the original terms for describing Ethernet drawn by Robert M. Metcalfe around 1976. ... For other uses, see Modem (disambiguation). ... For other uses, see Power band. ... It has been suggested that this article be split into articles entitled Synchronous optical networking, SONET and Synchronous digital hierarchy. ... There are very few or no other articles that link to this one. ... Optical fibers An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length. ... Coaxial Cable For the weapon, see coaxial weapon. ... 25 Pair Color Code Chart 10BASE-T UTP Cable Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. ... The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. ... The Internet Engineering Task Force (IETF) develops and promotes Internet standards, cooperating closely with the W3C and ISO/IEC standard bodies; and dealing in particular with standards of the TCP/IP and Internet protocol suite. ... A Network Management System (NMS) is a combination of hardware and software used to monitor and administer a network. ... The term network monitoring describes the use of a system that constantly monitors a computer network for slow or failing systems and that notifies the network administrator in case of outages via email, pager or other alarms. ... The word standard has several meanings: Classically, standard referred to a flag or banner; especially, a national or other ensign carried into battle; thus standard bearer indicates the one who bears, or carries, the standard. ... The application layer is the seventh level of the seven-layer OSI model. ... For other senses of this word, see protocol. ... A Logical schema is a data model of a specific problem domain that has more detail than a conceptual schema, but does not include the design considerations and physical storage parameters found in a physical schema. ... An object is fundamental concept in object-oriented programming. ...

SNMP exposes management data in the form of variables on the managed systems, which describe the system configuration. These variables can then be queried (and sometimes set) by managing applications.

Overview and basic concepts

In typical SNMP usage, there are a number of systems to be managed, and one or more systems managing them. A software component called an agent (see below) runs on each managed system and reports information via SNMP to the managing systems.

Essentially, SNMP agents expose management data on the managed systems as variables (such as "free memory", "system name", "number of running processes", "default route"). The managing system can retrieve the information through the GET, GETNEXT and GETBULK protocol operations or the agent will send data without being asked using TRAP or INFORM protocol operations. Management systems can also send configuration updates or controlling requests through the SET protocol operation to actively manage a system. Configuration and control operations are used only when changes are needed to the network infrastructure. The monitoring operations are usually performed on a regular basis.

The variables accessible via SNMP are organized in hierarchies. These hierarchies, and other metadata (such as type and description of the variable), are described by Management Information Bases (MIBs).

Management Information Bases (MIBs)

SNMP itself does not define which information (which variables) a managed system should offer. Rather, SNMP uses an extensible design, where the available information is defined by management information bases (MIBs). MIBs describe the structure of the management data of a device subsystem; they use a hierarchical namespace containing object identifiers (OID). Roughly speaking, each OID identifies a variable that can be read or set via SNMP. MIBs use the notation defined by ASN.1. A management information base (MIB) is a type of database used to manage the devices in a communications network. ... A namespace is a context in which a group of one or more identifiers might exist. ... It has been suggested that this article or section be merged into Identifier. ... In telecommunications and computer networking, Abstract Syntax Notation One (ASN.1) is a standard and flexible notation that describes data structures for representing, encoding, transmitting, and decoding data. ...

The MIB hierarchy can be depicted as a tree with a nameless root, the levels of which are assigned by different organizations. The top-level MIB OIDs belong to different standards organizations, while lower-level object IDs are allocated by associated organizations. This model permits management across all layers of the OSI reference model, extending into applications such as databases, email, and the Java EE reference model, as MIBs can be defined for all such area-specific information and operations. Layer may refer to: Look up Layer in Wiktionary, the free dictionary. ... Application software is a subclass of computer software that employs the capabilities of a computer directly and thoroughly to a task that the user wishes to perform. ... This article is about computing. ... E-mail, or email, is short for electronic mail and is a method of composing, sending, and receiving messages over electronic communication systems. ... Java EE is an object model reference for the Java EE Web server and application server environment. ...

A managed object (sometimes called a MIB object, an object, or a MIB) is one of any number of specific characteristics of a managed device. Managed objects comprise one or more object instances (identified by their OIDs), which are essentially variables.

Two types of managed objects exist:

1. Scalar objects define a single object instance.
2. Tabular objects define multiple related object instances that are grouped in MIB tables.

An example of a managed object is atInput, which is a scalar object that contains a single object instance, the integer value that indicates the total number of input AppleTalk packets on a router interface. A scalar may be: Look up scalar in Wiktionary, the free dictionary. ... The integers are commonly denoted by the above symbol. ... AppleTalk is a proprietary suite of protocols developed by Apple Inc for computer networking. ... In telecommunication and computer communication, the term network interface has the following meanings: The point of interconnection between a user terminal and a private or public network. ...

An object identifier (or object ID or OID) uniquely identifies a managed object in the MIB hierarchy.

Abstract Syntax Notation One (ASN.1)

Main article: Abstract Syntax Notation One

In telecommunications and computer networking, Abstract Syntax Notation One (ASN.1) is a standard and flexible notation that describes data structures for representing, encoding, transmitting, and decoding data. It provides a set of formal rules for describing the structure of objects that are independent of machine-specific encoding techniques and is a precise, formal notation that removes ambiguities. In telecommunications and computer networking, Abstract Syntax Notation One (ASN.1) is a standard and flexible notation that describes data structures for representing, encoding, transmitting, and decoding data. ... In telecommunications and computer networking abstract syntax notation one (ASN.1) is a standard, flexible method that describes data structures for representing, encoding, transmitting, and decoding data. ... A binary tree, a simple type of branching linked data structure. ... An encoder is a device used to encode a signal (such as a bitstream) or data into a form that is acceptable for transmission or storage. ...

ASN.1 is a joint ISO and ITU-T standard, originally defined in 1984 as part of CCITT X.409:1984. ASN.1 moved to its own standard, X.208, in 1988 due to wide applicability. The substantially revised 1995 version is covered by the X.680 series. In telecommunications and computer networking abstract syntax notation one (ASN.1) is a standard, flexible method that describes data structures for representing, encoding, transmitting, and decoding data. ... In telecommunications and computer networking abstract syntax notation one (ASN.1) is a standard, flexible method that describes data structures for representing, encoding, transmitting, and decoding data. ...

An adapted subset of ASN.1, Structure of Management Information (SMI), is specified in SNMP to define sets of related MIB objects; these sets are termed MIB modules. The Structure Of Management Information (SMI) is divided into three parts: module definitions, object definitions, and, notification definitions. ...

SNMP basic components

An SNMP-managed network consists of three key components:

1. Managed devices
2. Agents
3. Network-management systems (NMSs)

A managed device is a network node that contains an SNMP agent and that resides on a managed network. Managed devices collect and store management information and make this information available to NMSs using SNMP. Managed devices, sometimes called network elements, can be any type of device including, but not limited to, routers and access servers, switches and bridges, hubs, IP telephones, computer hosts, or printers. This article is about a computer networking device. ... A Network Access Server, or NAS, is a single point of access to a remote resource. ... A network switch is a computer networking device that connects network segments. ... A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. ... In general, a hub is a centre point: a wheels hub, which is the center of the wheel with spokes radiating out from it. ... What to say? Its a phone, but it encodes voice and transmits it via IP, using one of several CODECs, including G.711, G.728, and G.729. ... A computer printer, or more commonly a printer, produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper or transparencies. ...

An agent is a network-management software module that resides in a managed device. An agent has local knowledge of management information and translates that information into a form compatible with SNMP.

A network management system (NMS) executes applications that monitor and control managed devices. NMSs provide the bulk of the processing and memory resources required for network management. One or more NMSs may exist on any managed network. A Network Management System (NMS) is a combination of hardware and software used to monitor and administer a network. ...

SNMP protocol

SNMPv1 and SMI-specific data types

The SNMPv1 SMI specifies the use of a number of SMI-specific data types, which are divided into two categories:

1. Simple data types
2. Application-wide data types

Simple data types

Three simple data types are defined in the SNMPv1 SMI, all of which are unique values:

1. The integer data type is a signed integer in the range of -2³¹ to 2³¹-1.
2. Octet strings are ordered sequences of 0 to 65,535 octets.
3. Object IDs come from the set of all object identifiers allocated according to the rules specified in ASN.1.

Application-wide data types

Seven application-wide data types exist in the SNMPv1 SMI: network addresses, counters, gauges, time ticks, opaques, integers, and unsigned integers.

1. Network addresses represent an address from a particular protocol family. SNMPv1 supports only 32-bit IP addresses.
2. Counters are non-negative integers that increase until they reach a maximum value and then return to zero. In SNMPv1, a 32-bit counter size is specified.
3. Gauges are non-negative integers that can increase or decrease between specified minimum and maximum values. Whenever the system property represented by the gauge is outside of that range, the value of the gauge itself will vary no further than the respective maximum or minimum, as specified in RFC 2578.
4. A time tick represents a hundredth of a second since some event.
5. An opaque represents an arbitrary encoding that is used to pass arbitrary information strings that do not conform to the strict data typing used by the SMI.
6. An integer represents signed integer-valued information. This data type redefines the integer data type, which has arbitrary precision in ASN.1 but bounded precision in the SMI.
7. An unsigned integer represents unsigned integer-valued information and is useful when values are always non-negative. This data type redefines the integer data type, which has arbitrary precision in ASN.1 but bounded precision in the SMI.

SNMPv1 MIB tables

The SNMPv1 SMI defines highly structured tables that are used to group the instances of a tabular object (that is, an object that contains multiple variables). Tables are composed of zero or more rows, which are indexed in a way that allows SNMP to retrieve or alter an entire row with a single Get, GetNext, or Set command.

SNMPv2 and structure of management information

The SNMPv2 SMI is described in RFC 2578. It makes certain additions and enhancements to the SNMPv1 SMI-specific data types, such as including bit strings, network addresses, and counters. Bit strings are defined only in SNMPv2 and comprise zero or more named bits that specify a value. Network addresses represent an address from a particular protocol family. Counters are non-negative integers that increase until they reach a maximum value and then return to zero. In SNMPv1, a 32-bit counter size is specified. In SNMPv2, 32-bit and 64-bit counters are defined.

The SNMP protocol operates at the application layer (layer 7) of the OSI model. It specifies (in version 1) five core protocol data units (PDUs): The application layer is the seventh level of the seven-layer OSI model. ... The Open Systems Interconnection Basic Reference Model (OSI Reference Model or OSI Model for short) is a layered, abstract description for communications and computer network protocol design, developed as part of the Open Systems Interconnection (OSI) initiative. ... In telecommunications, the term protocol data unit (PDU) has the following meanings: Information that is delivered as a unit among peer entities of a network and that may contain control information, address information, or data. ...

1. GET REQUEST - used to retrieve a piece of management information.
2. GETNEXT REQUEST - used iteratively to retrieve sequences of management information.
3. GET RESPONSE - used by the agent to respond with data to get and set requests from the manager.
4. SET REQUEST - used to initialize and make a change to a value of the network element.
5. TRAP - used to report an alert or other asynchronous event about a managed subsystem. In SNMPv1, asynchronous event reports are called traps while they are called notifications in later versions of SNMP. In SMIv1 MIB modules, traps are defined using the TRAP-TYPE macro; in SMIv2 MIB modules, traps are defined using the NOTIFICATION-TYPE macro.

Other PDUs were added in SNMPv2, including: In telecommunications, the term protocol data unit (PDU) has the following meanings: Information that is delivered as a unit among peer entities of a network and that may contain control information, address information, or data. ...

1. GETBULK REQUEST - a faster iterator used to retrieve sequences of management information.
2. INFORM - an acknowledged trap.

Typically, SNMP uses UDP ports 161 for the agent and 162 for the manager. The Manager may send Requests from any available ports (source port) to port 161 in the agent (destination port). The agent response will be given back to the source port. The Manager will receive traps on port 162. The agent may generate traps from any available port.

Many distributions change this, however, and this is not necessarily always true.

SNMPv2 SMI information modules

The SNMPv2 SMI also specifies information modules, which specify a group of related definitions. Three types of SMI information modules[4] exist: MIB modules, compliance statements, and capability statements.

• MIB modules contain definitions of interrelated managed objects.
• Compliance statements provide a systematic way to describe a group of managed objects that must be implemented for conformance to a standard.
• Capability statements are used to indicate the precise level of support that an agent claims with respect to a MIB group. A NMS can adjust its behavior toward agents according to the capabilities statements associated with each agent.

SNMPv3

SNMPv3 is defined by RFC 3411–RFC 3418 (also known as 'STD0062'). SNMPv3 primarily added security and remote configuration enhancements to SNMP.^[2] SNMPv3 is the current standard version of SNMP as of 2004. The IETF has designated SNMPv3 a full Internet Standard,^[3] the highest maturity level for an RFC. It considers earlier versions to be obsolete (designating them "Historic").^[4] In December 1997 the "Simple Times" newsletter published several articles written by the SNMPv3 RFC editors explaining some of the ideas behind version 3 specifications.^[5] 2004 is a leap year starting on Thursday of the Gregorian calendar. ... The Internet Engineering Task Force (IETF) is charged with developing and promoting Internet standards. ... An Internet standard is a specification for an innovative internetworking technology or methodology, which the Internet Engineering Task Force (IETF) ratified as an open standard after the innovation underwent peer review. ... In internetworking and computer network engineering, Request for Comments (RFC) documents are a series of memoranda encompassing new research, innovations, and methodologies applicable to Internet technologies. ...

SNMPv3 provides important security features:^[6]

• Message integrity to ensure that a packet has not been tampered with in transit.

• Authentication to verify that the message is from a valid source.

• Encryption of packets to prevent snooping by an unauthorized source.

In computer science and telecommunications, the term data integrity has the following meanings: The condition in which data is identically maintained during any operation, such as transfer, storage, and retrieval. ... For other uses of the terms authentication, authentic and authenticity, see authenticity. ... Encrypt redirects here. ...

Development and usage

Version 1

SNMP version 1 (SNMPv1) is the initial implementation of the SNMP protocol. SNMPv1 operates over protocols such as User Datagram Protocol (UDP), Internet Protocol (IP), OSI Connectionless Network Service (CLNS), AppleTalk Datagram-Delivery Protocol (DDP), and Novell Internet Packet Exchange (IPX). SNMPv1 is widely used and is the de facto network-management protocol in the Internet community.

The first RFCs for SNMP, now known as SNMPv1, appeared in 1988: In internetworking and computer network engineering, Request for Comments (RFC) documents are a series of memoranda encompassing new research, innovations, and methodologies applicable to Internet technologies. ...

• RFC 1065 — Structure and identification of management information for TCP/IP-based internets
• RFC 1066 — Management information base for network management of TCP/IP-based internets
• RFC 1067 — A simple network management protocol

These protocols were obsoleted by:

• RFC 1155 — Structure and identification of management information for TCP/IP-based internets
• RFC 1156 — Management information base for network management of TCP/IP-based internets
• RFC 1157 — A simple network management protocol

After a short time, RFC 1156 (MIB-1) was replaced by more often used:

• RFC 1158 — Version 2 of management information base (MIB-2) for network management of TCP/IP-based internets

Version 1 has been criticized for its poor security. Authentication of clients is performed only by a "community string", in effect a type of password, which is transmitted in cleartext. The '80s design of SNMP V1 was done by a group of collaborators who viewed the officially sponsored OSI/IETF/NSF (National Science Foundation) effort (HEMS/CMIS/CMIP) as both unimplementable in the computing platforms of the time as well as potentially unworkable. SNMP was approved based on a belief that it was an interim protocol needed for taking steps towards large scale deployment of the Internet and its commercialization. In that time period Internet-standard authentication/security was both a dream and discouraged by focused protocol design groups.

Version 2

SNMPv2 (RFC 1441–RFC 1452), revises version 1 and includes improvements in the areas of performance, security, confidentiality, and manager-to-manager communications. It introduced GETBULK, an alternative to iterative GETNEXTs for retrieving large amounts of management data in a single request. However, the new party-based security system in SNMP v2, viewed by many as overly complex, was not widely accepted.

Community-Based Simple Network Management Protocol version 2, or SNMPv2c, is defined in RFC 1901–RFC 1908. In its initial stages, this was also informally known as SNMP v1.5. SNMP v2c comprises SNMP v2 without the controversial new SNMP v2 security model, using instead the simple community-based security scheme of SNMP v1. While officially only a "Draft Standard", this is widely considered the de facto SNMP v2 standard. De facto is a Latin expression that means in fact or in practice. It is commonly used as opposed to de jure (meaning by law) when referring to matters of law or governance or technique (such as standards), that are found in the common experience as created or developed without...

User-Based Simple Network Management Protocol version 2, or SNMP v2u, is defined in RFC 1909–RFC 1910. This is a compromise that attempts to offer greater security than SNMP v1, but without incurring the high complexity of SNMP v2. A variant of this was commercialized as SNMP v2*, and the mechanism was eventually adopted as one of two security frameworks in SNMP v3.

SNMPv1 & SNMPv2c interoperability

As presently specified, SNMPv2 is incompatible with SNMPv1 in two key areas: message formats and protocol operations. SNMPv2c messages use different header and protocol data unit (PDU) formats than SNMPv1 messages. SNMPv2c also uses two protocol operations that are not specified in SNMPv1. Furthermore, RFC 1908 defines two possible SNMPv1/v2c coexistence strategies: proxy agents and bilingual network-management systems.

Proxy agents

A SNMPv2 agent can act as a proxy agent on behalf of SNMPv1 managed devices, as follows:

• A SNMPv2 NMS issues a command intended for a SNMPv1 agent.
• The NMS sends the SNMP message to the SNMPv2 proxy agent.
• The proxy agent forwards Get, GetNext, and Set messages to the SNMPv1 agent unchanged.
• GetBulk messages are converted by the proxy agent to GetNext messages and then are forwarded to the SNMPv1 agent.

The proxy agent maps SNMPv1 trap messages to SNMPv2 trap messages and then forwards them to the NMS.

Bilingual network-management system

Bilingual SNMPv2 network-management systems support both SNMPv1 and SNMPv2. To support this dual-management environment, a management application in the bilingual NMS must contact an agent. The NMS then examines information stored in a local database to determine whether the agent supports SNMPv1 or SNMPv2. Based on the information in the database, the NMS communicates with the agent using the appropriate version of SNMP.

Version 3

The IETF recognizes Simple Network Management Protocol version 3 as defined by RFC 3411–RFC 3418 (also known as STD0062) as the current standard version of SNMP as of 2004. The IETF considers earlier versions as "Obsolete" or "Historical". The Internet Engineering Task Force (IETF) develops and promotes Internet standards, cooperating closely with the W3C and ISO/IEC standard bodies; and dealing in particular with standards of the TCP/IP and Internet protocol suite. ... 2004 is a leap year starting on Thursday of the Gregorian calendar. ...

In practice, SNMP implementations often support multiple versions: typically SNMPv1, SNMPv2c, and SNMPv3. See RFC 3584 "Coexistence between Version 1, Version 2, and Version 3 of the Internet-standard Network Management Framework".

SNMPv3 provides three important services: authentication, privacy and access control. For other uses of the terms authentication, authentic and authenticity, see authenticity. ... Data privacy refers to the evolving relationship between technology and the legal right to, or public expectation of privacy in the collection and sharing of data. ... Access control is the ability to permit or deny the use of something by someone. ...

Usage examples

• Monitoring device uptimes (sysUpTimeInstance)
• Inventory of OS versions (sysDescr)
• Collect interface information (ifName, ifDescr, ifSpeed, ifType, ifPhysAddr)
• Measuring network interface throughput (ifInOctets, ifOutOctets)
• Querying a remote ARP cache (ipNetToMedia)

Other SNMP topics

Autodiscovery

SNMP by itself is simply a protocol for collecting and organizing information. Most toolsets implementing SNMP offer some form of discovery mechanism, a standardized collection of data common to most platforms and devices, to get a new user or implementor started. One of these features is often a form of automatic discovery, where new devices discovered in the network are polled automatically. For SNMPv1 and SNMPv2c, this presents a security risk, in that your SNMP read communities will be broadcast in cleartext to the target device. While security requirements and risk profiles vary from organization to organization, care should be taken when using a feature like this, with special regard to common environments such as mixed-tenant datacenters, server hosting and colocation facilities, and similar environments.

Negative impact

SNMP implementations vary across platform vendors. In some cases, SNMP is often an added feature, and is not taken seriously enough to be an element of the core design. Some major equipment vendors tend to over extend their proprietary Command Line Interface (CLI) centric configuration and control systems ^[7]. This article or section does not adequately cite its references or sources. ...

SNMP's seemingly simple tree structure and linear indexing may not always be understood well enough within the internal data structures that are elements of a platform's basic design. As a result, processing SNMP query on certain data sets may result in higher CPU utilization than necessary. One example of this would be large routing tables, such as BGP or IGP . The Border Gateway Protocol (BGP) is the core routing protocol of the Internet. ... A set of routing protocols that are used within an autonomous system are referred to as interior gateway protocols (IGP). ...

Index adjusting

Modular devices may dynamically increase or decrease their indexes whenever slotted hardware is added or removed. Index values are typically assigned at boot time and remain fixed until the next reboot. Hardware added while the device is 'live' may have their indexes assigned at the end of the existing range and possibly reassigned at the next reboot. Network inventory and monitoring tools need to account for this behavior and properly react to the cold start trap from the device reboot in order to avoid corruption and mismatch polled data.

Plants and data centres

Server, rack and appliance operating temperatures and room humidity could be monitored remotely for SNMP enabled HVAC devices.[1][2] Rack-mounted redirects here. ... HVAC may also stand for High-voltage alternating current HVAC systems use ventilation air ducts installed throughout a building that supply conditioned air to a room through rectangular or round outlet vents, called diffusers; and ducts that remove air from return-air grilles Fire-resistance rated mechanical shaft with HVAC...

Security implications

1. SNMP versions 1 and 2c are subject to packet sniffing of the clear text community string from the network traffic, because they do not implement encryption.
2. All versions of SNMP are subject to brute force and dictionary attacks for guessing the community strings/authentication strings, because they do not implement a challenge-response handshake.
3. Although SNMP works over TCP and other protocols, it is most commonly used over UDP which is connectionless and vulnerable to IP spoofing attacks. Thus, all versions are subject to bypassing device access lists that might have been implemented to restrict SNMP access, though SNMPv3's other security mechanisms should prevent a successful attack.
4. SNMP's configuration (write) capabilities can be misconfigured and used to cause severe damage. These 'write' capabilities are very rarely used in practice, partly due to lack of security in SNMP versions before SNMPv3 and partly due to the fact that many devices do not implement SNMP configuration interfaces.
5. SNMP tops the list of the SANS Institute's Common Default Configuration Issues with the issue of default SNMP community strings set to ‘public’ and ‘private’ and is number ten on the SANS The Top 10 Most Critical Internet Security Threats for the year 2000.

For more detail on SNMP security implications see the CERT SNMP Vulnerabilities FAQ A packet sniffer (also known as a network analyzer or protocol analyzer or, for particular types of networks, an Ethernet sniffer or wireless sniffer) is computer software or computer hardware that can intercept and log traffic passing over a digital network or part of a network. ... The EFFs US$250,000 DES cracking machine contained over 1,800 custom chips and could brute force a DES key in a matter of days — the photograph shows a DES Cracker circuit board fitted with several Deep Crack chips. ... In cryptanalysis and computer security, a dictionary attack is a technique for defeating a cipher or authentication mechanism by trying to determine its decryption key or passphrase by searching a large number of possibilities. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. ... In computer networking, the term Internet Protocol spoofing (IP spoofing) is the creation of IP packets with a forged (spoofed) source IP address. ... The SANS Institute (SysAdmin, Audit, Networking, and Security) is a trade name owned by the for-profit Escal Institute of Advanced Technologies. ... For other meanings of CERT, see CERT (disambiguation) The CERT/CC (Computer Emergency Response Team Coordination Center) was created by DARPA in November 1988 after the Morris Worm struck. ...

RFCs

• RFC 1155 — Structure and Identification of Management Information for the TCP/IP-based Internets
• RFC 1156 — Management Information Base for Network Management of TCP/IP-based internets
• RFC 1157 — A Simple Network Management Protocol (SNMP)
• RFC 1441 — Introduction to version 2 of the Internet-standard Network Management Framework
• RFC 1213 — Management Information Base for Network Management of TCP/IP-based internets: MIB-II
• RFC 3410 (Informational) — Introduction and Applicability Statements for Internet Standard Management Framework
• RFC 3411 (Standard 62) — An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks
• RFC 3412 (Standard 62) — Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)
• RFC 3413 (Standard 62) — Simple Network Management Protocol (SNMP) Application
• RFC 3414 (Standard 62) — User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)
• RFC 3415 (Standard 62) — View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP)
• RFC 3416 (Standard 62) — Version 2 of the Protocol Operations for the Simple Network Management Protocol (SNMP)
• RFC 3417 (Standard 62) — Transport Mappings for the Simple Network Management Protocol (SNMP)
• RFC 3418 (Standard 62) — Management Information Base (MIB) for the Simple Network Management Protocol (SNMP)
• RFC 3584 (Best Current Practice) — Coexistence between Version 1, Version 2, and Version 3 of the Internet-standard Network Management Framework
• RFC 3826 (Proposed) — The Advanced Encryption Standard (AES) Cipher Algorithm in the SNMP User-based Security Model

See also

• Management information base (MIB)
• Object identifier (OID)
• Remote monitoring (RMON)
• AgentX, a subagent protocol for SNMP
• Simple Gateway Monitoring Protocol (SGMP), an obsolete protocol replaced by SNMP
• Common management information protocol (CMIP), a management protocol by ISO/OSI used by telecommunications devices
• Common management information service (CMIS),
• CMIP over TCP/IP (CMOT)
• Net-SNMP, an open source reference implementation of SNMP

A management information base (MIB) is a type of database used to manage the devices in a communications network. ... It has been suggested that this article or section be merged into Identifier. ... RMON stands for Remote Monitoring. ... SNMP agent extensibility or AgentX is a computer networking protocol used as a standardized framework for extensible Simple Network Management Protocol agents and the procedure by which those agents process SNMP protocol messages. ... Simple Gateway Monitoring Protocol (SGMP) defined in RFC 1028, allows commands to be issued to application protocol entities to set or retrieve values (integer or octet string types) for use in monitoring the gateways on which the application protocol entities reside. ... Common Management Information Protocol (CMIP) is a protocol for network management, it defines the communication between network management applications and management agents. ... In telecommunication, a common management information service (CMIS) is a service that specifies the service interface to the Common Management Information Protocol (CMIP). ... CMOT may stand for CMIP (Common management interface protocol) Over TCP/IP Cut-Me-Own-Throat Dibbler (character in novel by Terry Pratchett) Categories: ... Net-SNMP is a suite of software for using and deploying the SNMP protocol (v1, v2c and v3 and the AgentX subagent protocol). ...

External links

• Description of the SNMP packet breakdown
• SNMP FAQ part 1
• SNMP FAQ part 2
• SNMP products and technical articles
• Cisco's description of SNMP and how to use in their products
• Articles by SNMP Research

Implementations

• Net-SNMP (Net-SNMP: Open source SNMP implementation)
• Netsnmpj: Open source SNMP for Java
• OpenSNMP: multi-threaded SNMPv3 engine
• PySNMP: pure-Python module, BSD license
• TinySNMP: an easy to configure minimal SNMPv1 agent
• SNMP.NET V3
• iReasoning MIB Browser / SNMP Manager (Free)
• Net::SNMP : a pure Perl module that implements SNMPv1, v2 and v3 on IPv4 and IPv6
• SNMP4J - Free SNMP API for Java Managers and Agents
• Synapse: Open source Synchronous TCP/IP Library for Pascal/Delphi

• versatile-serializing.net, .NET library, contains a SNMP V2C implementation
• SNMP Manager LoriotPro free edition

Net-SNMP is a suite of software for using and deploying the SNMP protocol (v1, v2c and v3 and the AgentX subagent protocol). ...

References

1. ^ RFC 3411 — An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks
2. ^ SNMP Version 3 links hub
3. ^ RFC Editor List of current Internet Standards (STDs)
4. ^ RFC Editor List of HISTORIC RFCs
5. ^ In This Issue: SNMP Version 3 The Simple Times ISSN 1060-6080
6. ^ SNMPv3 Cisco
7. ^ SNMP Research presentations in favor of standards-based management over proprietary CLIs