Home > Articles > Cisco > CCNA Security

SNMP Concepts and Configuration

The Simple Network Management Protocol (SNMP) is a common site in most networks, it provides not only a method that can be used for event notification but can also be used to maintain device statistics, set configuration parameters and many other functions. This article takes a look at some of the basic SNMP concepts, examining how it works and how it can be configured to perform basic functions.
Like this article? We recommend

The Simple Network Management Protocol (SNMP) is a common site in most networks. It not only provides a method that can be used for event notification but also can be used to maintain device statistics, set configuration parameters, and many other functions. This article takes a look at some of the basic SNMP concepts, how SNMP works, and how it can be configured to perform basic functions.

SNMP Concepts

SNMP is a protocol that operates at the application layer; it defines a method of communication between various networking devices and a central manager for use with the monitoring and management of these devices.

SNMP Components

There are three different components that are defined by SNMP:

  • SNMP manager—The SNMP manager is a central system that is used to monitor traffic seen by the various SNMP agents as well as provide a mechanism for the control of these agents.
  • SNMP agent—The SNMP agent is a software component that exists within a network element; this component is used to maintain real-time information about the elements operations. The agent is also used to communicate this information back to the central SNMP manager as well as perform control actions dictated by the SNMP manager.
  • Management Information Base (MIB)—The MIB is a virtual information storage location where network management information is held. Within the MIB are a number of different collections of objects that are related together (think database). Each of these collections contains a number of variables that can be altered by the SNMP agent and/or SNMP manager.

SNMP Versions

There are three different versions of SNMP that can be configured:

  • SNMPv1—This was the original version of SNMP; SNMPv1 utilizes a community based security mechanism.
  • SNMPv2c—This was created to update a number of little things within SNMPv1; SNMPv2c utilizes a community based security mechanism.
  • SNMPv3—This was developed to provide a much higher level of security then was provided by either previous version. A couple different security features are implemented within the SNMPv3 standard; these include:
    • Message integrity
    • Authentication
    • Encryption

SNMP Security Models

When implementing SNMP, there are five different security models that can be implemented depending on the version of SNMP being used and the amount of security required. Table 1 below shows the different features of each available model and what authentication and encryption they support.

Table 1—SNMP Security Models

Model

Level

Authentication

Encryption

v1

noAuthNoPriv

Community String

None

v2c

NoAuthNoPriv

Community String

None

v3

NoAuthNoPriv

Username

None

v3

AuthNoPriv

MD5 or SHA

None

v3

AuthPriv

MD5 or SHA

DES, 3DES, AES

SNMP Operations

Once the different elements within the network have been configured, they are able to provide a number of different operations that are used to provide the majority of the work done by SNMP. The available operations depend on what version of SNMP is being run on the network.

The following operations are available when using all of the available versions:

  • Get—The Get operation is used by the SNMP manager to retrieve one or more object instances from the SNMP agent.
  • GetNext—The GetNext operation is used by the SNMP manager to retrieve the next object instance from the SNMP agent.
  • Set—The Set operation is used by the SNMP manager to set the value of an object instance on the SNMP agent.

The following operation was added in SNMPv2c:

  • GetBulk—The GetBulk operation is used by the SNMP manager to efficiently retrieve large amounts (multiple rows) of data from the SNMP agent.

SNMP also defines different notification operations that can be used by the SNMP to notify the SNMP manager of a significant event. The following notification operation was defined in SNMPv1:

  • Trap—The Trap notification operation is used to send an unacknowledged message from the SNMP agent to the SNMP manager.

The following notification operation was added in SNMPv2c:

  • Inform—The Inform notification operation is used to send an acknowledged message from the SNMP agent to the SNMP manager.

Note that while the Trap notification operation was defined in SNMPv1, the format of the Trap message was altered in SNMPv2c.

SNMP Configuration

Regardless of the version of SNMP implemented, there are a number of different parameters that are shared. The configuration of these parameters is shown in Table 2.

Table 2—General SNMP Parameter Configuration

Step 1

Enter privileged mode

router>enable

Step 2

Enter global configuration mode

router#configure terminal

Step 3

Configure the SNMP contact information

router(config)#snmp-server contact text

Step 4

Configure the SNMP location information

router(config)#snmp-server location text

Step 5

Configure the SNMP chassis-id

router(config)#snmp-server chassis-id number

Step 6

Configure an SNMP view; a view can be used to limit the type of information that is accessible.

router(config)#snmp-server view view-name oid-tree {included | excluded}

Step 7

Exit configuration mode

router(config)#end

The configuration of how an SNMP agent communicated to the SNMP manager depends on the version of SNMP being implemented. SNMPv1 and SNMPv2c utilize community strings to authenticate with the SNMP agent and manager. The configuration required to setup this relationship between the SNMP agent and SNMP manager when implementing these versions is shown in Table 3.

Table 3—SNMP v1/v2c Configuration

Step 1

Enter privileged mode

router>enable

Step 2

Enter global configuration mode

router#configure terminal

Step 3

Configure the SNMP community.

The view-name is used to limit the variable that is accessible to those accessing the SNMP agent using a specific community string.

The access-list-number refers to an access list that can contain a list of ip addresses of SNMP manager that are allowed to access the SNMP agent.

router(config)#snmp-server community string [view view-name] [ro | rw] [access-list-number]

Step 4

Exit configuration mode

router(config)#end

The configuration of a SNMPv3 agent is a bit more involved, as it requires the setup of users and groups that are used to authenticate with the SNMP manager. Another piece of information that is required when configuring this connection is the SNMPV3 EngineID of the remote host; this EngineID exists on each SNMPv3 element and is typically automatically created. The configuration required to setup when SNMPv3 is being implemented is shown in Table 4.

Table 4—SNMP v3 Configuration

Step 1

Enter privileged mode

router>enable

Step 2

Enter global configuration mode

router#configure terminal

Step 3

Configure the remote EngineID of the SNMP manager

router(config)#snmp-server engineID remote remote-ip-address remote-engineID


Configure the SNMPv3 group

router(config)#snmp-server group group-name v3 {auth | noauth | priv} [read read-view] [write write-view] [notify notify-view]

Step 4

Configure the SNMPv3 user associated with the SNMP manager and its associated parameters

router(config)#snmp-server user username groupname remote remote-ip-address [udp-port udp-port] v3 [encrypted] [auth {md5 | sha} auth-password] [priv {des | 3des | aes {128 | 192 |256}} priv-password]

Step 5

Exit configuration mode

router(config)#end

The configuration that is required to set up the use of SNMP traps or informs is the same regardless of the version of SNMP being used. The configuration required to setup these on the SNMP agent are shown in Table 5.

Table —SNMP Trap or Inform Configuration

Step 1

Enter privileged mode

router>enable

Step 2

Enter global configuration mode

router#configure terminal

Step 3

Configure the location where SNMP traps or informs will be sent.

Traps are sent by default

router(config)#snmp-server host host [traps | informs] [version {1 | 2c | 3 [auth | noauth | priv]}] {community-name | username}

Step 4

Configuring the sending of traps or informs.

Whether the SNMP agent sends traps or informs is configured with the snmp-server host command.

router(config)#snmp enable traps [notification-type]

Step 5

Exit configuration mode

router(config)#end

Summary

The deployment of SNMP has been a long time staple within the network of many organizations. What has not been as commonly deployed is the use of SNMPv3, as it does require a different type of configuration that is a bit more time consuming. If possible, a deployment or update to the use of SNMPv3 is recommended as it does provide a much more secure management solution. Hopefully, the information in this article has clearly shown the possibilities that are available when deploying SNMP and how the different versions differ from each other.

Pearson IT Certification Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Pearson IT Certification and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Pearson IT Certification products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.pearsonitcertification.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020