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- [Instructor] The Simple Network Management Protocol

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is integral to every enterprise.

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It allows network admins to gather statistical information

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from network connected devices,

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workstations, servers, firewalls,

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routers, switches, printers,

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virtually any network connected device.

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SNMP is heavily used by Network Management Systems or NMS'

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that poll, trend, and alert on network and server status.

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In the SNMP environment,

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the server doing collections is known as the manager.

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The manager will generally directly run

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a network management station.

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This is the software package

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responsible for doing collection and storage.

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Some larger designs will distribute polling engines

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in geographic areas.

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Polling engine is a piece of software

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that will issue SNMP requests to manage devices' agents.

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An agent is a software package

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that will respond to SNMP requests from managers.

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In short, the agent runs on the device you want to monitor.

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SNMP can be either read-only or read/write.

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Read is the ability to only retrieve information.

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Read/write gives you the ability to change information

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on a remote device.

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Writing can be used to adjust informational data

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or do things like disable or enable switch ports.

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Whenever an SNMP agent is going to be polled,

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the information is retrieved

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by asking for specific object identifiers or OIDs.

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OIDs are long streams of numbers in dotted notation.

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For example, the OID for system description

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is 1.3.6.1.2.1.1.1.

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Think of this like an index.

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Management Information Bases, or MIBs, will take these OIDs

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and map them to a hierarchical human-readable form.

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MIBs aren't always necessary for SNMP's function,

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but it makes it much easier to utilize.

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MIBs generally make it easier to add new monitoring points

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into an existing network monitoring system.

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Agents' requests are received on UDP port 161.

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SNMP traps are sent to UDP port 162.

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Traps are messages that are sent from an agent to a manager

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when some defined event occurs.

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When using TLS for encryption,

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an agent listens on UDP port 10161

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and traps are sent on UDP 10162.

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SNMPv1 and V2C both implement a simple

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community-based authentication system.

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A community is basically just a plaintext password

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sent to an agent.

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In v3, there were three main additions:

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confidentiality by encrypting packets,

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integrity to ensure packets haven't been tempered with,

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and authentication to validate the source.

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Having a solid NMS is core to administrator sanity.

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SNMP allows an administrator to see trends.

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SNMP allows an administrator to see trends, predict issues,

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and react with speed and confidence.