scrippy_snmp

Basic SNMP capabilities for the Scrippy framework.

Prerequisites

Python

Python >= 3.10 (tested with Python 3.11).

Python modules

List of required modules

The modules listed below will be automatically installed.

• pysnmp

Installation

Manual

git clone https://codeberg.org/scrippy/scrippy-snmp.git
cd scrippy-snmp
python -m pip install -r requirements.txt
make install

With pip

pip install scrippy-snmp

Usage

This module allows basic SNMP operations such as get, walk and set.

it supports SNMP version 1 and version 2. Version 3 is still in depveloppment.

Limitation: asynchronous contexts

The Snmp methods (get, walk and set) are synchronous: each call blocks until the remote host answers (or the timeout expires) and returns the result directly.

Internally, they rely on the asyncio API of pysnmp and run each request with asyncio.run(). As a consequence, they cannot be called from a thread where an asyncio event loop is already running, for example:

• from within an async def function,
• from a Jupyter notebook,
• from an asynchronous framework (FastAPI, aiohttp, ...).

In such a context, the call raises:

RuntimeError: asyncio.run() cannot be called from a running event loop

If you need to use this module from asynchronous code, run the call in a separate thread:

import asyncio
from scrippy_snmp.snmp import Snmp

async def main():
  snmp = Snmp(host=HOST, port=PORT, community=RO_COMMUNITY, version=VERSION)
  location = await asyncio.to_thread(snmp.get, LOCATION_OID)

Regular (synchronous) scripts are not affected by this limitation.

SNMP operations

Setup

As in shell SNMP implementation it is first needed to set the connection up, typically by providing the remote hostname or IP address, the UDP port on which join the host and the community string which is a sort of secret identifier that is allowed to perform some operations on the remote host.

from scrippy_snmp.snmp import Snmp

HOST = "127.0.0.1"
PORT = 161
RO_COMMUNITY = "read-only-community"
RW_COMMUNITY = "read-write-community"
VERSION = "2c"

snmp = Snmp(host=HOST, port=PORT, community=RO_COMMUNITY, version=VERSION)

Get

The get operation allows to retrieve a specific OID value:

LOCATION_OID = ".1.3.6.1.2.1.1.6.0"

snmp = Snmp(host=HOST, port=PORT, community=RO_COMMUNITY, version=VERSION)
location = snmp.get(LOCATION_OID)

print(location)
("SNMPv2-MIB::sysLocation.0", "Room 42")

The return value is a 2 elements Tuple containing:

• The OID in text format
• The OID value

Walk

The walk operation allow to retrieve a collection of OID value directly under the specified OID

SYSTEM_OID = ".1.3.6.1.2.1.1"

snmp = Snmp(host=HOST, port=PORT, community=RO_COMMUNITY, version=VERSION)
result = snmp.walk(SYSTEM_OID)

for value in result:
  print(value)

('SNMPv2-MIB::sysDescr.0', 'arcadia.local.mcos.nc 1148685499 FreeBSD 13.2-RELEASE')
('SNMPv2-MIB::sysObjectID.0', 'SNMPv2-SMI::enterprises.12325.1.1.2.1.1')
('SNMPv2-MIB::sysUpTime.0', '320223')
('SNMPv2-MIB::sysContact.0', 'sysmeister@example.com')
('SNMPv2-MIB::sysName.0', 'scrippy.example.com')
('SNMPv2-MIB::sysLocation.0', 'Room 42')
...

The return value is a list of 2 elements Tuples, each containing:

• The OID in text format
• The OID value

Set

The set operation allows to set the value of a specific writtable OID.

LOCATION_OID = ".1.3.6.1.2.1.1.6.0"

snmp = Snmp(host=HOST, port=PORT, community=RW_COMMUNITY, version=VERSION)
snmp.set(oid=LOCATION_OID, value="Room 200", datatype="str")
location = snmp.get(LOCATION_OID)

print(location)
("SNMPv2-MIB::sysLocation.0", "Room 200")

Note:

• The Snmp object must have been set up with a community with write permission on the remote host
• The datatype must be provided to the Snmp.set() method (see below for available datatypes)
• The Snmp.set() method does not return any value.

Available data types