- [Instructor] The Simple Network Management Protocol
is integral to every enterprise.
It allows network admins to gather statistical information
from network connected devices,
workstations, servers, firewalls,
routers, switches, printers,
virtually any network connected device.
SNMP is heavily used by Network Management Systems or NMS'
that poll, trend, and alert on network and server status.
In the SNMP environment,
the server doing collections is known as the manager.
The manager will generally directly run
a network management station.
This is the software package
responsible for doing collection and storage.
Some larger designs will distribute polling engines
in geographic areas.
Polling engine is a piece of software
that will issue SNMP requests to manage devices' agents.
An agent is a software package
that will respond to SNMP requests from managers.
In short, the agent runs on the device you want to monitor.
SNMP can be either read-only or read/write.
Read is the ability to only retrieve information.
Read/write gives you the ability to change information
on a remote device.
Writing can be used to adjust informational data
or do things like disable or enable switch ports.
Whenever an SNMP agent is going to be polled,
the information is retrieved
by asking for specific object identifiers or OIDs.
OIDs are long streams of numbers in dotted notation.
For example, the OID for system description
is 1.3.6.1.2.1.1.1.
Think of this like an index.
Management Information Bases, or MIBs, will take these OIDs
and map them to a hierarchical human-readable form.
MIBs aren't always necessary for SNMP's function,
but it makes it much easier to utilize.
MIBs generally make it easier to add new monitoring points
into an existing network monitoring system.
Agents' requests are received on UDP port 161.
SNMP traps are sent to UDP port 162.
Traps are messages that are sent from an agent to a manager
when some defined event occurs.
When using TLS for encryption,
an agent listens on UDP port 10161
and traps are sent on UDP 10162.
SNMPv1 and V2C both implement a simple
community-based authentication system.
A community is basically just a plaintext password
sent to an agent.
In v3, there were three main additions:
confidentiality by encrypting packets,
integrity to ensure packets haven't been tempered with,
and authentication to validate the source.
Having a solid NMS is core to administrator sanity.
SNMP allows an administrator to see trends.
SNMP allows an administrator to see trends, predict issues,
and react with speed and confidence.