Python – How to Obtain the Configuration of a Networking Device using NETCONF

Introduction

Within this article we will look at how to interact with a networking device (Cisco CSR) using the NETCONF protocol. To do so, we will use the Python module – ncclient.

What is NETCONF

First of all, What is NETCONF?

NETCONF (NETwork CONFiguration) is a protocol defined by the IETF to “install, manipulate, and delete the configuration of network devices”.
– www.tail-f.com

Further details can be found within our previous article – An Introduction to NETCONF/YANG.

Dependencies

First of all we will need to install some Python dependencies,

pip install ncclient pyang pyangbind xmltodict

Connect

Now that we have the required packages installed we can connect to the device. Like so,

from ncclient import manager

m = manager.connect(host='10.29.1.133', port=830, username='cisco',
                    password='cisco', device_params={'name': 'csr'})

print m.connected

...

True

Get Capabilities

In order to obtain the devices capabilities we can use the method server_capabilities.

for c in m.server_capabilities:
    print c

...

urn:ietf:params:xml:ns:yang:smiv2:SNMP-FRAMEWORK-MIB?module=SNMP-FRAMEWORK-MIB&revision=2002-10-14

urn:ietf:params:xml:ns:yang:cisco-policy-target?module=cisco-policy-target&revision=2016-03-30
urn:ietf:params:xml:ns:yang:smiv2:CISCO-CBP-TARGET-TC-MIB?module=CISCO-CBP-TARGET-TC-MIB&revision=2006-03-24
urn:ietf:params:netconf:capability:notification:1.0

Get Configuration

To fetch the running configuration of the device you can simply run,

running_config = m.get_config('running')

This will provide us with the variable running_config containing the configuration within an XML data type. Lets pretty print the XML,

import xmltodict
import xml.dom.minidom

print(xml.dom.minidom.parseString(str(running_config)).toprettyxml())

...

<rpc-reply message-id="urn:uuid:01290b52-a324-454b-b754-f8513b0d3b0d" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
        <data>
                <native xmlns="http://cisco.com/ns/yang/Cisco-IOS-XE-native">
                        <version>16.5</version>
                        <boot-start-marker></boot-start-marker>
                        <boot-end-marker></boot-end-marker>
                        <service>
                                <timestamps>
                                        <debug>
                                                <datetime>
                                                        <msec></msec>
                                                </datetime>
                                        </debug>
                                        <log>
                                                <datetime>
                                                        <msec></msec>
                                                </datetime>
                                        </log>
                                </timestamps>
                        </service>
                        <platform>
                                <console xmlns="http://cisco.com/ns/yang/Cisco-IOS-XE-platform">
                                        <output>serial</output>
                                </console>
                        </platform>
                        <hostname>csr1000v-1</hostname>
                        <enable>
                                <password>
                                        <secret>cisco</secret>
                                </password>
...

JSON

In addition we can also interact with the configuration by parsing our running_config variable into a dict().

conf_json = xmltodict.parse(str(running_config))
conf_json['rpc-reply']["data"]["native"]["hostname"]

...

u'csr1000v'

Close Session

Finally, once all of the necessary operations have been completed we close the session.

m.close_session()

...

<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="urn:uuid:ebb48b66-185e-4
7ac-9820-73418ed0790f" xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0"><ok></ok></rpc-reply>
Rick Donato

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