SNMP-PassPersist

This module is a SNMP passpersist backend for Net-SNMP.

The snmp_passpersist.PassPersist class present a convenient way to creare a MIB subtree and expose it to snmp via its passpersist protocol. Two threads are used, one for talking with snmpd and a second that trigger the update process at a fixed interval.

The keyword 'DUMP' has been added to the protocol for testing purpose.

Installation

The easiest way is using pip :

pip install snmp_passpersist

Example

Usage example: in a file /path/to/your/script.py :

#!/usr/bin/python -u

import snmp_passpersist as snmp

def update():
        pp.add_int('0.1', 123, "This is a label for this integer")
        pp.add_str('0.2', "A string")
        pp.add_oct('0.3', '01 00 1f 0b 00 0b') # MAC address as an octet string

pp=snmp.PassPersist(".1.3.6.1.3.53.8")
pp.start(update,30) # Every 30s

With the following line in Net-SNMP's snmpd.conf :

pass_persist    .1.3.6.1.3.53.8.0     /path/to/your/script.py

A Real-world example is available here: https://github.com/nagius/cxm/blob/master/misc/snmp_xen.py

List of supported types and their helpers

Type	Helper
Counter32	add_cnt_32bit()
Counter64	add_cnt_64bit()
GAUGE	add_gau()
INTEGER	add_int()
IPADDRESS	add_ip()
OBJECTID	add_oid()
OCTET	add_oct()
STRING	add_str()
TIMETICKS	add_tt()

Special helpers

Labels

You can add a label with each entries, as an optional parameter to all add_*() helpers. This label is not used by Net-SNMP and is only useful for debugging with the DUMP keyword.

add_oid()

This helper allow you to add a simple OID string and give it the proper type. For example, calling this method with

pp.add_oid('.1.3.6.1.2.1.47','1.1.1.1.3.1','0.0')

where "0.0" represents SNMPv2-SMI::zeroDotZero.

This results in the following response when we walk this OID:

ENTITY-MIB::entPhysicalVendorType.1 = OID: SNMPv2-SMI::zeroDotZero

Set an attribute

You can register a helper to allow the recording of value from Net-SNMP.

def my_setter(oid, type, value):
        print("Received %s with value %s for oid %s." % (type, value, oid))
        return True

pp.register_setter('.1.3.6.1.3.53.8.0.4', my_setter)

Example for debugging :

$ /path/to/your/script.py
set
.1.3.6.1.3.53.8.0.4
INTEGER 987
Received INTEGER with value 987 for oid .1.3.6.1.3.53.8.0.4.
DONE
set
.1.3.6.1.3.53.8.0.1
STRING some-random-useless-string
not-writable

Another example that show the usage of the 'set' feature is available in the 'example/' directory.

Debugging example

Run the previous script in a shell and type the commands :

$ /path/to/your/script.py
PING
PONG
DUMP
{'0.1': {'type': 'INTEGER', 'value': '123'}}
get
.1.3.6.1.3.53.8
NONE
get
.1.3.6.1.3.53.8.0.1
.1.3.6.1.3.53.8.0.1
INTEGER
123
getnext
.1.3.6.1.3.53.8
.1.3.6.1.3.53.8.0.1
INTEGER
123

All commands are typed on two lines : get.1.3.6.1.3.53.8.0.1, except PING and DUMP.

Credits

Many thanks to all contributors.