SNMPv3

SNMPv3 is an enhanced standard for SNMP that improves the security and privacy of SNMP access to managed devices and provides sophisticated control of access to the device MIB. The prior standard versions of SNMP, SNMPv1, and SNMPv2c, provided no privacy and little security.

Note

If you downgrade from ExtremeXOS 15.6 to a lower version, the SNMPv3 users do not work if the configuration was saved in 15.6. The SNMPv3 users must be manually created again.

The following RFCs provide the foundation for the Extreme Networks implementation of SNMPv3:

• RFC 3410, Introduction to version 3 of the Internet-standard Network Management Framework, provides an overview of SNMPv3.
• RFC 3411, An Architecture for Describing SNMP Management Frameworks, talks about SNMP architecture, especially the architecture for security and administration.
• RFC 3412, Message Processing and Dispatching for the Simple Network Management Protocol (SNMP), talks about the message processing models and dispatching that can be a part of an SNMP engine.
• RFC 3413, SNMPv3 Applications, talks about the different types of applications that can be associated with an SNMPv3 engine.
• RFC 3414, The User-Based Security Model for Version 3 of the Simple Network Management Protocol (SNMPv3), describes the User-Based Security Model (USM).
• RFC 3415, View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP), talks about VACM as a way to access the MIB.
• RFC 3826, The Advanced Encryption Standard (AES) Cipher Algorithm in the SNMP User-based Security Model.

Note

AES 192 and AES 256 bit encryption are proprietary implementations and may not work with some SNMP Managers.

The SNMPv3 standards for network management were driven primarily by the need for greater security and access control. The new standards use a modular design and model management information by cleanly defining a message processing (MP) subsystem, a security subsystem, and an access control subsystem.

The MP subsystem helps identify the MP model to be used when processing a received Protocol Data Unit (PDU), which are the packets used by SNMP for communication.

The MP layer helps in implementing a multilingual agent, so that various versions of SNMP can coexist simultaneously in the same network.

The security subsystem features the use of various authentication and privacy protocols with various timeliness checking and engine clock synchronization schemes.

SNMPv3 is designed to be secure against:

• Modification of information, where an in-transit message is altered.
• Masquerades, where an unauthorized entity assumes the identity of an authorized entity.
• Message stream modification, where packets are delayed and/or replayed.
• Disclosure, where packet exchanges are sniffed (examined) and information is learned about the contents.

The access control subsystem provides the ability to configure whether access to a managed object in a local MIB is allowed for a remote principal. The access control scheme allows you to define access policies based on MIB views, groups, and multiple security levels.

In addition, the SNMPv3 target and notification MIBs provide a more procedural approach for generating and filtering of notifications.

SNMPv3 objects are stored in non-volatile memory unless specifically assigned to volatile storage. Objects defined as permanent cannot be deleted.

Note

In SNMPv3, many objects can be identified by a human-readable string or by a string of hexadecimal octets. In many commands, you can use either a character string, or a colon-separated string of hexadecimal octets to specify objects. To indicate hexadecimal octets, use the keyword hex in the command.