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NETCONF Python Script – Hostname & Version Retrieval (IOS XE)

Overview

This script demonstrates how to use NETCONF with Python (ncclient) to connect to a Cisco IOS XE device and retrieve basic device information using YANG subtree filtering.

Specifically, it retrieves:

  • Device hostname
  • IOS XE software version

The script connects to the Catalyst 8000v DevNet Sandbox device using NETCONF over SSH (port 830).

Prerequisites

1. Network Access

  • Active connection to the Cisco DevNet Sandbox VPN
  • Reachable device IP: 10.10.20.48

2. Python Environment

Python 3.8+ recommended

Install required packages:

pip install ncclient lxml

3. Device Access Details

Parameter Value
Host 10.10.20.48
Port 830
Username developer
Password C1sco12345

Script Purpose

This script performs the following actions:

  1. Opens a NETCONF session to an IOS XE device
  2. Sends a <get> request with a YANG subtree filter

  3. Requests only:

  4. <hostname>

  5. <version>
  6. Prints the raw XML response
  7. Parses and displays the extracted values in human‑readable form

Download Script

Click to download the script directly:

Download NETCONF_Hostname_Version_Retrieval.py

Full Script

#!/usr/bin/env python

from lxml import etree
from ncclient import manager

# Connection details
username = "developer"
password = "C1sco12345"
hostname = "10.10.20.48"
port = 830

# Establish NETCONF connection
device = manager.connect(
    host=hostname,
    port=port,
    username=username,
    password=password,
    hostkey_verify=False,
    allow_agent=False,
    look_for_keys=False
)

# Define YANG subtree filter
xml_filter = """
<native xmlns="http://cisco.com/ns/yang/Cisco-IOS-XE-native">
  <version />
  <hostname />
</native>
"""

# Send NETCONF get request
netconf_response = device.get(('subtree', xml_filter))

# Print raw XML response
print('XML Response:')
print('-' * 80)
print(etree.tostring(netconf_response.data_ele, pretty_print=True).decode('utf-8'))

# Namespace mapping for XPath queries
ns_find = {
    None: "http://cisco.com/ns/yang/Cisco-IOS-XE-native",
}

# Extract values from XML
device_hostname = netconf_response.data.find(".//hostname", namespaces=ns_find).text
device_version = netconf_response.data.find(".//version", namespaces=ns_find).text

# Display parsed results
print('-' * 80)
print(f'Hostname: {device_hostname}')
print(f'Version: {device_version}')
print("\n")

# Close NETCONF session
device.close_session()

How It Works (Step‑by‑Step)

1. Establishing NETCONF Connection

device = manager.connect(...)
  • Opens an SSH-based NETCONF session to port 830
  • Disables host key checking (safe for lab use)
  • Uses password authentication only

2. Building the YANG Subtree Filter

<native xmlns="http://cisco.com/ns/yang/Cisco-IOS-XE-native">
  <version />
  <hostname />
</native>

This filter:

  • Targets Cisco’s native IOS XE YANG model
  • Requests only two elements
  • Reduces payload size and improves efficiency

3. Sending the NETCONF Request

netconf_response = device.get(('subtree', xml_filter))
  • Executes a NETCONF <get> RPC
  • Applies subtree filtering
  • Returns only the requested data

4. Printing Raw XML Output

This section prints the <data> portion of the NETCONF reply for inspection and debugging.

5. Parsing XML with Namespaces

ns_find = { None: "http://cisco.com/ns/yang/Cisco-IOS-XE-native" }

Cisco YANG models use XML namespaces. This mapping allows XPath queries to locate elements correctly.

6. Extracting Values

device_hostname = ...
device_version = ...
  • Searches the XML tree for <hostname> and <version>
  • Extracts their text values

7. Displaying Results

Example output:

Hostname: CAT8KV-1
Version: 17.12.02

How to Run

  1. Make sure VPN is connected
  2. Save script as get_device_info.py
  3. Run:
python3 get_device_info.py

Expected Output

You will see:

  1. Raw XML NETCONF response
  2. Parsed values:
Hostname: CAT8KV-1
Version: 17.12.02

Security Notes

  • hostkey_verify=False is acceptable for labs only
  • Do NOT hardcode credentials in production
  • Use SSH keys and environment variables for real systems

References