Pure Python Script for BGP Peer State Sensor

This is a pure python script for polling BGP Peer states where the BGP4-MIB is available for polling.
It will report the current state of all BGP peers, and send a warning if any state other than "ESTABLISHED" is polled. This has been tested against Cisco routers , but it should work for any router/switch running IEEE MIBS
Disclaimer: Use at your own risk, preferably after testing thoroughly.
This script was tested on the local probe. See PRTG documentation for running python scripts on a remote probe

Steps:

Pip upgrade and install pysnmp
Open a command prompt, change directory to the following: cd C:\Program Files (x86)\PRTG Network Monitor\python\Scripts Run the following commands to upgrade pip and install pysnmp and pysnmp SMIs pip install pip --upgrade pip install pysnmp pysmi
Copy the following text into a text file, and save it as C:\Program Files (x86)\PRTG Network Monitor\lookups\custom\customsensor.bgp4.peerstatus.ovl

<?xml version="1.0" encoding="UTF-8"?>
<ValueLookup id="customsensor.bgp4.peerstatus" desiredValue="6" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="PaeValueLookup.xsd">
	<Lookups>
		<SingleInt state="Error" value="1">Idle</SingleInt>
		<SingleInt state="Error" value="2">Connect</SingleInt>
		<SingleInt state="Error" value="3">Active</SingleInt>
		<SingleInt state="Error" value="4">Open Sent</SingleInt>
		<SingleInt state="Error" value="5">Open Confirm</SingleInt>
		<SingleInt state="Ok" value="6">Established</SingleInt>
	</Lookups>
</ValueLookup>

Load Lookups in the PRTG Web Dashboard:
Setup > System Administration > Load Lookups and File Lists > Go!

Copy the following text into a text file, and save it as C:\Program Files (x86)\PRTG Network Monitor\Custom Sensors\python\bgp_peers.py

from pysnmp.hlapi import *
from prtg.sensor.result import CustomSensorResult
from prtg.sensor.units import ValueUnit
import sys
import re
import json

prtg_params = json.loads(sys.argv[1])


def bgp_peer_walk(host):
  oid = '.1.3.6.1.2.1.15.3.1.2'
  reg_ex = re.compile('[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+ = [1-6]')
  bgp_peer_dict = {}

  for (errorIndication,
   errorStatus,
   errorIndex,
   varBinds) in nextCmd(SnmpEngine(), 
                        CommunityData(prtg_params['snmpcommv2']),
                        UdpTransportTarget((host, 161)),
                        ContextData(),                                                           
                        ObjectType(ObjectIdentity(oid)),
                        lexicographicMode=False):
    if errorIndication:
      csr = CustomSensorResult(text="Python Script pysnmp error")
      csr.error = f"Python Script pysnmp error: {errorIndication}"
      print(csr.json_result)
      sys.exit()
    elif errorStatus:
      csr = CustomSensorResult(text="Python Script pysnmp error")
      csr.error = f"Python Script pysnmp error: {errorStatus}"
      print(csr.json_result)            
      sys.exit()
    else:
      for varBind in varBinds:
        bgp_peers = reg_ex.search(str(varBind))
        ip, state = str(bgp_peers.group(0)).split(' = ')
        bgp_peer_dict[ip] = state
  return(bgp_peer_dict)

def build_csr(peer_dict):
  try:
    csr = CustomSensorResult()
    for peer in peer_dict:
      if peer_dict[peer] is '6':
        csr.add_channel(name = peer, value = 6, unit = ValueUnit.CUSTOM, is_warning = 0, value_lookup="customsensor.bgp4.peerstatus")
      if peer_dict[peer] is '5':
        csr.add_channel(name = peer, value = 5, unit = ValueUnit.CUSTOM, is_warning = 1, value_lookup="customsensor.bgp4.peerstatus")
      if peer_dict[peer] is '4':
        csr.add_channel(name = peer, value = 4, unit = ValueUnit.CUSTOM, is_warning = 1, value_lookup="customsensor.bgp4.peerstatus")
      if peer_dict[peer] is '3':
        csr.add_channel(name = peer, value = 3, unit = ValueUnit.CUSTOM, is_warning = 1, value_lookup="customsensor.bgp4.peerstatus")
      if peer_dict[peer] is '2':
        csr.add_channel(name = peer, value = 2, unit = ValueUnit.CUSTOM, is_warning = 1, value_lookup="customsensor.bgp4.peerstatus")
      if peer_dict[peer] is '1':
        csr.add_channel(name = peer, value = 1, unit = ValueUnit.CUSTOM, is_warning = 1, value_lookup="customsensor.bgp4.peerstatus")
    print(csr.json_result)
  except Exception as e:
    csr = CustomSensorResult(text="Python build_csr execution error")
    csr.error = f"Python Script execution error: {e}"
    print(csr.json_result)

build_csr(bgp_peer_walk(prtg_params['host']))

To setup the sensor, Click Add Sensor, and search for Python Script Advanced.
On the configuration page, rename the Sensor, select the Transmit SNMP credentials bullet, and click save.

bgp bgp-peer custom-python-script python-script-advanced-sensor