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, works with Python 2.4 up to Python 3.7

Rendered PySMI documentation can be found at pysmi site.

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.py tool).

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

$ mibdump.py --generate-mib-texts  --destination-format json IF-MIB
Source MIB repositories: file:///usr/share/snmp/mibs, http://mibs.snmplabs.com/asn1/@mib@
Borrow missing/failed MIBs from: http://mibs.snmplabs.com/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 http://mibs.snmplabs.com/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.

You could pip install pysmi or download it from PyPI.

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. All rights reserved.