SNMP - Simple Network Management Protocol

SNMP stands for Simple Network Management Protocol. It's a protocol used primarily to monitor and manage devices on computer networks. SNMP provides a standardized framework and a common language used for the monitoring and management of devices in a networked environment.

Here are some key concepts and features associated with SNMP:

  1. Agents and Managers:
    • Agent: This is a software module that resides in a managed device. An agent has local knowledge of management information and can translate that information to/from the SNMP protocol.
    • Manager: It's software that runs on a workstation or server and is used to query agents and sometimes set values on the agents. Managers collect information from agents, request actions from them, and even send them configurations.
  2. MIB (Management Information Base):
    • The MIB is like a database schema for the network device. It's a hierarchical structure that uses a tree format. Every item in the tree can be identified by a unique series of numbers, called an OID (Object Identifier).
    • A MIB file is often provided by hardware manufacturers and describes the properties of the device that can be read or sometimes set.
  3. OID (Object Identifier):
    • Each individual piece of information that can be accessed via SNMP is identified using a unique sequence of numbers, known as an OID.
    • OIDs are organized hierarchically and can be represented in a dot-decimal format (e.g., 1.3.6.1.2.1.1).
  4. SNMP Versions:
    • SNMPv1: The original version. It's widely supported but has significant security weaknesses.
    • SNMPv2c: This version improved some aspects of v1 and introduced the Inform request. It uses a simple text password (called a community string) for authentication.
    • SNMPv3: The most secure version, it adds security features like authentication and encryption.
  5. Community Strings: In SNMPv1 and v2c, a community string acts like a password. There are often two types of community strings:
    • Read-Only (RO): Allows you to view the MIB variables but not change them.
    • Read-Write (RW): Allows both viewing and setting the MIB variables.
  6. Operations:
    • Basic SNMP operations include GET, SET, GETNEXT, and GETBULK.
    • GET retrieves the value of a specific OID.
    • SET changes the value of a specific OID.
    • GETNEXT retrieves the value of the next OID in the MIB tree.
    • GETBULK is used for retrieving voluminous data from large MIB tables.
  7. Traps and Informs: These are unsolicited messages sent by SNMP agents to managers. A trap might indicate something like a reboot, a configuration change, or a failure. Informs are similar to Traps but they expect a response from the manager, acknowledging receipt.
  8. Security Concerns: SNMP, especially versions 1 and 2c, has been criticized for its security weaknesses. SNMPv3 addressed many of these concerns by introducing features like message integrity, authentication, and encryption.

https://networklessons.com/cisco/ccie-enterprise-infrastructure/introduction-to-snmp

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