SNMPv2c vs SNMPv3 custom MIB

Question

I'm writing a custom MIB that is spec'd to be SNMPv3 compliant. Right now, I know that it is SNMPv2c compliant (through smilint and other tools). Is there anything that I need to do with the MIB to make it SNMPv3 compliant?

The plan is to use SNMPv3 w/USM, so I believe an SNMPv2c MIB with Net-SNMP configured for USM meets these requirements. I'm just a little concerned that my MIB isn't specifying any privacy requirements, such as authNoPriv. Is that really done just through configuration files (in Net-SNMP), and not through the MIB at all?

Information on writing MIB's specifically for SNMPv3 is pretty sparse, so I'm just looking for some confirmation that I'm doing things correctly.

Here's an "example" object in the MIB file that is pretty exemplary of the rest of the file.

example OBJECT-TYPE
    SYNTAX
        Unsigned32 (1..4294967295)
    MAX-ACCESS
        read-only
    STATUS
        current
    DESCRIPTION
        "Example information."
    ::= { exampleEntry 2 }

SNMP v3 introduced new message format and authentication/privacy models, but it does not change much of SMI. For Net-SNMP, authentication/privacy is configured via `conf` files only like you discovered. There is nothing in your MIB documents to control that. — Lex Li, Sep 25 '18 at 04:24
@LexLi, Thanks for the clarification. I have an additional `Net-SNMP` question posted here if you happen to be familiar with the software: https://stackoverflow.com/questions/52487820/multiple-sub-agents-for-one-table-in-net-snmp — zeus_masta_funk, Sep 25 '18 at 18:04

score 0 · Accepted Answer · edited Oct 07 '21 at 11:10

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You want to write your MIB conforming SMIv2 as specified in RFC 2578 https://www.rfc-editor.org/rfc/rfc2578 .

edited Oct 07 '21 at 11:10

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answered Sep 24 '18 at 15:11

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Ok - so to follow up, writing my MIB SMIv2 conformant and implementing USM at the "config" level in Net-SNMP is the correct route, correct? – zeus_masta_funk Sep 24 '18 at 21:37
Yes. In order to interoperate with the widest possible set of NMS applications, use standard MIBs (RFCs) as much as possible. If you don't care about other applications but your own, you can do anything you want. – Gambit Support Sep 25 '18 at 12:21

score 0 · Answer 2 · edited Oct 07 '21 at 13:33

You do not write MIBs to be "compliant to SNMPv3", or to any other version of SNMP. This has no meaning. MIBs describe a data interface, whereas SNMP is a way of transporting/exposing that interface across a network (others exist).

The relevant standards, when writing MIBs, are SMIv1 and SMIv2.

It is a good idea to write your MIBs to be SMIv2 compliant, because that's what "modern" technology expects.

But this has nothing to do with SNMPv2c vs SNMPv3.

SNMPv2c vs SNMPv3 custom MIB

2 Answers2