PyPNM MIB Compiler

Command-Line Utility To Precompile SNMP OIDs Into A Python Dictionary.

Purpose

Convert all MIB definitions in mibs/ into a flat Python dictionary (COMPILED_OIDS) and write it to:

src/pypnm/snmp/compiled_oids.py

The file is overwritten on each run and includes a UTC timestamp. Precompiling avoids runtime MIB parsing, reduces startup latency, and improves stability.

How It Works

1. Runs snmptranslate -Tz against local MIBs in mibs/.
2. Captures raw symbol→OID output.
3. Parses into a de-duplicated {name: numeric_oid} map.
4. Emits compiled_oids.py with the COMPILED_OIDS constant and a generated-on timestamp.

Directory Structure

PyPNM/
├── mibs/                         # Input MIB files (.txt/.my)
├── src/pypnm/snmp/               # Target module
│   └── compiled_oids.py          # Auto-generated dictionary
└── tools/
    └── update_snmp_oid_dict.py   # Compiler script

Prerequisites

Python

• Python 3.6 or newer.

Net-SNMP (snmptranslate)

Debian/Ubuntu:

sudo apt update && sudo apt install -y snmp snmp-mibs-downloader

RHEL/Fedora:

sudo dnf install -y net-snmp-utils

Verify:

which snmptranslate
snmptranslate -V

curl (optional, for fetching MIBs)

sudo apt install -y curl

Populate mibs/ (Top Level Only)

Fetch current CableLabs DOCSIS MIBs into mibs/ without descending into subdirectories (e.g., archive/):

curl -s https://mibs.cablelabs.com/MIBs/DOCSIS/ \
| grep -oP '(?<=href=")[^"/]+\.(my|txt)(?=")' \
| while read -r file; do
  wget -nc "https://mibs.cablelabs.com/MIBs/DOCSIS/$file" -P mibs/
done

You may also place vendor/private MIBs in mibs/; they will be included automatically.

Usage

From the repository root:

python3 tools/snmp/update-snmp-oid-dict.py

Example output:

Generating compiled OIDs from MIBs...
Compiled 782 OIDs to src/pypnm/snmp/compiled_oids.py

Output Format

compiled_oids.py contains a single map with a timestamp header:

# Auto-generated OID dictionary from snmptranslate -Tz
# Do not modify manually. Generated on: 2025-07-06T20:15:45.123456Z

COMPILED_OIDS = {
    "sysDescr": "1.3.6.1.2.1.1.1",
    "docsIf3CmtsCmUsStatusRxPower": "1.3.6.1.4.1.1166.1.19.2.3.1.6",
    ...
}

Verifying The Result

Quick sanity checks:

python3 - <<'PY'
from src.pypnm.snmp.compiled_oids import COMPILED_OIDS
assert "sysDescr" in COMPILED_OIDS
assert COMPILED_OIDS["sysDescr"].startswith(("1.", ".1."))
print(f"OK: {len(COMPILED_OIDS)} OIDs loaded")
PY

Optional cross-check with snmptranslate:

snmptranslate -On sysDescr
# Expect: .1.3.6.1.2.1.1.1

Environment & Options

If your snmptranslate environment requires explicit MIB paths, set:

export MIBDIRS=./mibs
export MIBS=+ALL

For vendor MIBs in additional directories:

export MIBDIRS="./mibs:/opt/vendor/mibs"

The compiler script prefers local mibs/ and does not need system-wide MIBs when your set is complete.

Troubleshooting

• snmptranslate: cannot find module Ensure files exist in mibs/, and set MIBDIRS=./mibs and MIBS=+ALL.

• Zero OIDs compiled Check tool output for errors; confirm snmptranslate -Tz runs successfully on your host.

• Name collisions If different MIBs export the same symbol, the last win applies. Prefer authoritative MIBs in mibs/ and remove stale/duplicate vendor variants.

• Non-DOCSIS environments The compiler is generic; place any MIB set into mibs/ to generate a unified dictionary.

Notes

• compiled_oids.py is generated; do not edit manually.
• Re-run the compiler after adding or updating MIB files to refresh the dictionary.