pysnmp-pysmi 2.3.0

SNMP MIB parser

PySMI is a pure-Python implementation of SNMP SMI MIB parser. This tool is designed to turn ASN.1 MIBs into various formats. As of this moment, JSON and pysnmp modules can be generated from ASN.1 MIBs.

Features

• Understands SMIv1, SMIv2 and de-facto SMI dialects
• Turns MIBs into pysnmp classes and JSON documents
• Maintains an index of MIB objects over many MIB modules
• Automatically pulls ASN.1 MIBs from local directories, ZIP archives, HTTP and FTP servers
• 100% Python, requires Python 3.10 or newer

How to use PySMI

If you are using pysnmp, you might never notice pysmi presence - pysnmp calls pysmi for MIB download and compilation behind the scenes (you can still can do that manually by invoking mibdump tool).

To turn ASN.1 MIB into a JSON document, call mibdump tool like this:

$ mibdump --generate-mib-texts  --destination-format json IF-MIB
Source MIB repositories: file:///usr/share/snmp/mibs, https://pysnmp.github.io/mibs/asn1/@mib@
Borrow missing/failed MIBs from: http://pysnmp.github.io/json/fulltexts/@mib@
Existing/compiled MIB locations: 
Compiled MIBs destination directory: .
MIBs excluded from code generation: RFC-1212, RFC-1215, RFC1065-SMI, RFC1155-SMI,
RFC1158-MIB, RFC1213-MIB, SNMPv2-CONF, SNMPv2-SMI, SNMPv2-TC, SNMPv2-TM
MIBs to compile: IF-MIB
Destination format: json
Parser grammar cache directory: not used
Also compile all relevant MIBs: yes
Rebuild MIBs regardless of age: yes
Do not create/update MIBs: no
Byte-compile Python modules: no (optimization level no)
Ignore compilation errors: no
Generate OID->MIB index: no
Generate texts in MIBs: yes
Keep original texts layout: no
Try various filenames while searching for MIB module: yes
Created/updated MIBs: IANAifType-MIB, IF-MIB, SNMPv2-MIB
Pre-compiled MIBs borrowed: 
Up to date MIBs: SNMPv2-CONF, SNMPv2-SMI, SNMPv2-TC
Missing source MIBs: 
Ignored MIBs: 
Failed MIBs: 

JSON document build from IF-MIB module would hold information such as:

   {
      "ifMIB": {
          "name": "ifMIB",
          "oid": "1.3.6.1.2.1.31",
          "class": "moduleidentity",
          "revisions": [
            "2007-02-15 00:00",
            "1996-02-28 21:55",
            "1993-11-08 21:55"
          ]
        },
      ...
      "ifTestTable": {
        "name": "ifTestTable",
        "oid": "1.3.6.1.2.1.31.1.3",
        "nodetype": "table",
        "class": "objecttype",
        "maxaccess": "not-accessible"
      },
      "ifTestEntry": {
        "name": "ifTestEntry",
        "oid": "1.3.6.1.2.1.31.1.3.1",
        "nodetype": "row",
        "class": "objecttype",
        "maxaccess": "not-accessible",
        "augmention": {
          "name": "ifTestEntry",
          "module": "IF-MIB",
          "object": "ifEntry"
        }
      },
      "ifTestId": {
        "name": "ifTestId",
        "oid": "1.3.6.1.2.1.31.1.3.1.1",
        "nodetype": "column",
        "class": "objecttype",
        "syntax": {
          "type": "TestAndIncr",
          "class": "type"
        },
        "maxaccess": "read-write"
      },
      ...
   }

In general, converted MIBs capture all aspects of original (ASN.1) MIB contents and layout. The snippet above is just a partial example, but here is the complete IF-MIB.json file.

Besides one-to-one MIB conversion, PySMI library can produce JSON index to facilitate fast MIB information lookup across large collection of MIB files. For example, JSON index for IP-MIB.json, TCP-MIB.json and UDP-MIB.json modules would keep information like this:

   {
      "compliance": {
         "1.3.6.1.2.1.48.2.1.1": [
           "IP-MIB"
         ],
         "1.3.6.1.2.1.49.2.1.1": [
           "TCP-MIB"
         ],
         "1.3.6.1.2.1.50.2.1.1": [
           "UDP-MIB"
         ]
      },
      "identity": {
          "1.3.6.1.2.1.48": [
            "IP-MIB"
          ],
          "1.3.6.1.2.1.49": [
            "TCP-MIB"
          ],
          "1.3.6.1.2.1.50": [
            "UDP-MIB"
          ]
      },
      "oids": {
          "1.3.6.1.2.1.4": [
            "IP-MIB"
          ],
          "1.3.6.1.2.1.5": [
            "IP-MIB"
          ],
          "1.3.6.1.2.1.6": [
            "TCP-MIB"
          ],
          "1.3.6.1.2.1.7": [
            "UDP-MIB"
          ],
          "1.3.6.1.2.1.49": [
            "TCP-MIB"
          ],
          "1.3.6.1.2.1.50": [
            "UDP-MIB"
          ]
      }
   }

With this example, compliance and identity keys point to MODULE-COMPLIANCE and MODULE-IDENTITY MIB objects, oids list top-level OIDs branches defined in MIB modules. Full index build over thousands of MIBs could be seen here.

The PySMI library can automatically fetch required MIBs from HTTP, FTP sites or local directories. You could configure any MIB source available to you (including https://pysnmp.github.io/mibs/asn1) for that purpose.

How to get PySMI

The pysmi package is distributed under terms and conditions of 2-clause BSD license. Source code is freely available as a GitHub repo.

Run uv add pysnmp-pysmi or pip install pysnmp-pysmi, or download it from PyPI. Note the name: pysmi is the original, unmaintained package.

To try the command-line tools without installing anything permanently:

$ uvx --from pysnmp-pysmi mibdump --help

How to develop PySMI

PySMI uses uv for dependency management, builds and releases.

$ uv sync            # create .venv and install everything, including dev tools
$ uv run pytest      # run the test suite
$ uv run mibdump --help

Linting, formatting and type checking are run through pre-commit, which is what CI checks:

$ uv run pre-commit install     # optional, to run these on every commit
$ uv run pre-commit run --all-files

That covers ruff for linting and formatting, and mypy for type checking. To build the documentation:

$ uv run sphinx-build -b html docs/source docs/build

If something does not work as expected, open an issue at GitHub or post your question on Stack Overflow.

Copyright (c) 2015-2020, Ilya Etingof. Copyright (c) 2024-2026, the PySNMP maintainers. All rights reserved.