SNMP (Simple Network management protocol)

An internet protocol for collecitn, organizing, and modifiying informaton about managed devices on IP networks.

Managed deviced - any device that can communicate with an SNMP manager

SNMP Manager - any machine on network running snmp protocol to colleoct and process

SNMP agents - devices that are sending info about themselves back to the snmp manager.

set - manager to agent .. change value of a variable.

get manger to agent .. retreve the value of a variable from the agent to the manger.

trap - agent to manager. agent notify manager of real time events.

ex uptime, config changes, unexpected downtime of a link..

granulatr trap - each SNMP trap has an OID

OID, Identifies a vriable that can be read or setMIB used to describe thesstructure of the managemtn data of a device subsystem using hierarchel namespace.

MIb - used to desribed the management strudc data of a hierachale namespace.

SNMP traps don’t send redundant info.

verbose trap - configured to contain all info about a given alert.

Variable binding - data stored in a key value configuration.

snmpv1 use community string to give access to their security mechanasim. default community strings are publice or private and are a security risk.

v2

v3 - newest most secure.

intregrithy - hash messages

authengication - source validation

confidentiality - encryption DES 56 bit key or AES if you have a firmware upgrade. groups comonets into different componets.

📡 SNMP (Simple Network Management Protocol)

Definition:

Internet protocol for collecting, organizing, and modifying information about managed devices on IP networks.

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🔑 Components

• Managed Devices
  • Any device running an SNMP agent (routers, switches, servers, printers).
• SNMP Manager
  • Central system running SNMP software.
  • Collects/processes info from agents.
• SNMP Agents
  • Run on devices.
  • Send info back to SNMP manager.

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📊 Core Operations

• GET → Manager asks agent for variable value.
• SET → Manager changes a variable on agent.
• TRAP → Agent notifies manager of an event (e.g., link down).
• Variable Binding → Key-value pairs that define SNMP data.

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🗂️ MIB & OIDs

• MIB (Management Information Base):
  • Defines the structure of managed data in a hierarchical namespace.
• OID (Object Identifier):
  • Unique identifier for each variable that can be read/set.

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🛎️ Traps

• Granular Trap → Only includes specific OID(s).
• Verbose Trap → Includes full context/details for the event.
• Traps don’t send redundant info → only triggered events.

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🔐 SNMP Versions

• SNMPv1
  • Uses community strings (“public” / “private”).
  • ⚠️ Weak security (plaintext).
• SNMPv2c
  • Adds bulk transfers, still uses community strings.
  • Slightly improved performance, still insecure.
• SNMPv3 (most secure, recommended)
  • Adds:
    • integrity → hash messages to prevent tampering.
    • Authentication → validate source.
    • Confidentiality → encryption (DES 56-bit, or AES if supported).

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✅ Exam Tips

• Trap = agent → manager notification.
• GET/SET = manager ↔ agent requests.
• MIB = database structure; OID = unique variable identifier.
• SNMPv1/v2 = insecure (plaintext community strings).
• SNMPv3 = secure (encryption, authentication, integrity).
• Default community strings = BIG risk → must be changed.