Why doesn't the simplest example from the easysnmp library work?

Question

Python

In general, I decided to understand the SNMP protocol. What's what and so on. After reading a little theory and understanding the very basics, I decided to quickly start practicing in Python. But something went wrong: even the simplest example from the official documentation does not work.

from easysnmp import Session

# Create an SNMP session to be used for all our requests
session = Session(hostname='localhost', community='public', version=2)

# You may retrieve an individual OID using an SNMP GET
location = session.get('sysLocation.0')

# You may also specify the OID as a tuple (name, index)
# Note: the index is specified as a string as it can be of other types than
# just a regular integer
contact = session.get(('sysContact', '0'))

# And of course, you may use the numeric OID too
description = session.get('.1.3.6.1.2.1.1.1.0')

# Set a variable using an SNMP SET
session.set('sysLocation.0', 'The SNMP Lab')

# Perform an SNMP walk
system_items = session.walk('system')

# Each returned item can be used normally as its related type (str or int)
# but also has several extended attributes with SNMP-specific information
for item in system_items:
    print '{oid}.{oid_index} {snmp_type} = {value}'.format(
        oid=item.oid,
        oid_index=item.oid_index,
        snmp_type=item.snmp_type,
        value=item.value
    )

And here is the error:

Traceback (most recent call last):
  File "/home/meksvinz/PycharmProjects/easysnmp/1.py", line 4, in <module>
    snmp_get('sysDescr.0', hostname='localhost', community='public', version=1)
  File "/home/meksvinz/projects/envs/snmp/lib/python3.7/site-packages/easysnmp/easy.py", line 22, in snmp_get
    return session.get(oids)
  File "/home/meksvinz/projects/envs/snmp/lib/python3.7/site-packages/easysnmp/session.py", line 315, in get
    interface.get(self, varlist)
SystemError: <built-in function get> returned NULL without setting an error

The script was launched from a virtual environment (by the way, in IPython the exact same crap).
Please tell me what is the reason for this error. I could not figure it out myself because of the catastrophically small amount of information on the network.

Answer 1

snmpd installed?

Answer 2

There's a compatibility bug with python3.7 at the C level of the module. I was looking for how to fix this some time ago, and I managed to fix it. The patch is here: https://github.com/kamakazikamikaze/easysnmp/pull/117
And you can install the corrected one for python3.7 here: https://github.com/nerosketch/easysnmp.git.
pip install git+ https://github.com/nerosketch/easysnmp.git