Paramiko vs Netmiko: Key Differences for Network Automation

As networks continue to scale in size and complexity, automation has become critical for managing configurations and reducing repetitive tasks. Python has emerged as a popular language for network automation. Within its ecosystem, Paramiko and Netmiko have emerged as two leading tools for interfacing with network gear programmatically.

But what is the difference between these two Python libraries? When might you choose one over the other? In this comprehensive, 2600+ word guide, I‘ll explore the history, capabilities, usage and key differentiators between Paramiko and Netmiko for network automation.

A Brief History of Paramiko and Netmiko

First, some background on the origins of these two technologies.

Paramiko

Paramiko was created in 2003 by security researcher Jeff Forcier. He built it because he needed more SSH functionality for Python than what the builtin ssh library provided at the time.

The first release provided basic SSH client support, SFTP client/server capabilities and ssh-agent support. These foundational capabilities made Paramiko a versatile tool for automating remote services over SSH.

Over subsequent releases, additional features like ssh tunneling/port-forwarding, key signing, proxy commands, multi-channel support and more were added. The project is open-source, actively maintained and released under the GPL license.

Netmiko

Netmiko emerged more recently in 2016, created by network engineer Kirk Byers. His goal was to build an easy-to-use SSH library specifically for configuring and managing network devices like routers and switches.

Netmiko debuted with support for over a dozen network platforms from vendors like Cisco, Juniper, Arista and HP. It provided convenience methods like send_command and send_config to simplify executing show commands and pushing device configurations.

The project has seen rapid adoption thanks to its simplicity, performance and multi-vendor support. As of 2024, Netmiko boasts over 7 million downloads per year and over 3300 GitHub stars. It is MIT licensed open-source software.

Real-World Use Cases

While both tools enable SSH automation for networks, they tend to excel in different real-world scenarios based on their capabilities.

Paramiko Use Cases

Here are some examples of where the flexibility of Paramiko provides an advantage:

• Securely copying files to network devices as part of an automation workflow. This takes advantage of Paramiko‘s SFTP integrations.

• Establishing persistent SSH tunnels into restrictive network environments that only allow inbound SSH connections from specific jump boxes.

• Automating legacy gear that may not be directly supported by other tools like Netmiko. Since Paramiko gives lower-level SSH access, custom integrations can be built.

Netmiko Use Cases

Some real-world scenarios where Netmiko delivers the most value:

• Multi-vendor network configurations across Cisco, Juniper, Arista etc. Netmiko understands the nuances of each platform and optimizes the interaction.

• Rapid sending of bulk commands like showing interface stats across an estate of 10,000 devices. Netmiko‘s speed and output handling shines here.

• Validation of ACL, route policies, etc. by parsing outputs after a change. Netmiko‘s result filtering simplifies this.

The above are just a subset of real usage examples. But it showcases why understanding the tools‘ Sweet spots matters when selecting one.

Popularity and Adoption Stats

Paramiko and Netmiko enjoy broad usage, but direct apples-to-apples comparisons can be difficult since Paramiko has existed longer. Still, looking at package downloads and GitHub activity provides useful proxy metrics for adoption levels:

Paramiko Stats

• 7+ million PyPI downloads in 2022
• 1,500+ GitHub stars
• 450+ forks
• Over 700 closed issues and PRs, indicating an active contributor community

Netmiko Stats

• 7+ million PyPI downloads in 2022
• 3,300+ GitHub stars
• 1,100+ forks
• Over 2,300 closed issues and PRs
• 88 contributors, showing it is a vibrant open source project

Based solely on these metrics, Netmiko appears to have outpaced Paramiko in recent years – at least within the network automation niche. But Paramiko maintains an impressive level of usage as a general purpose SSH library.

Code Comparison: Netmiko vs Paramiko

Let‘s now analyze some side-by-side code samples using both libraries to highlight the differences developers experience working with each.

Simple SSH Connection

First, establishing a basic SSH session to a Cisco router:

# Netmiko
from netmiko import ConnectHandler  

device = ConnectHandler(
   device_type=‘cisco_ios‘,
   host=‘router1‘, 
   username=‘netauto‘, 
   password=‘Cisco123‘
)

print(device.find_prompt())

# Paramiko 
import paramiko

ssh = paramiko.SSHClient()
ssh.connect("router1", username="netauto", password="Cisco123")

ssh_stdin, ssh_stdout, ssh_stderr = ssh.exec_command("show ip int brief")
output = ssh_stdout.read()
print(output)

Even for simple connectivity, Netmiko requires less code and abstraction away from the raw SSH protocol.

Sending Multiple Commands

Now sending a sequence of show commands:

# Netmiko 
output1 = device.send_command("show version")
output2 = device.send_command("show ip int brief")  

print(output1)
print(output2)

# Paramiko
stdin, stdout, stderr = ssh.exec_command("show version")  
version = stdout.read()

stdin, stdout, stderr = ssh.exec_command("show ip int brief")
interfaces = stdout.read()   

print(version)
print(interfaces)

You can observe how Netmiko simplifies executing multiple command executions. No need to re-establish channel connectivity each time.

Enabling Configuration Mode

Pushing new configurations:

# Netmiko
device.config_mode() 
device.send_config_set(["hostname Router2", "ip name-server 1.2.3.4"])  

# Paramiko 
stdin, stdout, stderr = ssh.exec_command("configure terminal")  

stdin.write("hostname Router2\n")
stdin.write("ip name-server 1.2.3.4\n")
stdin.channel.send_exit_status()

print(stdout.read())

For sending config changes, Netmiko simplifies control flow around entering config mode. The channel dance in Paramiko is more complex.

The above illustrates why for network-specific tasks, Netmiko delivers significant developer experience benefits. But Paramiko provides more flexibility for generalized SSH workflows.

Architectural Differences

Beyond surface area capabilities, understanding some core architectural differences between these two SSH libraries helps explain their performance and functionality divergences.

Paramiko Architecture

As a lower-level SSH library, Paramiko exposes much of the SSH protocol directly to developers. Interacting with a remote host involves channel initialization, sending commands, handling responses and channel finalization. Multi-channel support allows simulating an interactive terminal session over SSH protocol channels.

This architecture gives developers flexibility, but also burdens them with tracking more state. Protocol intricacies leak through the API as well.

Netmiko Architecture

Netmiko inserts an abstraction layer to simplify much of the SSH work needed for network gear automation. Methods like send_command encapsulate channel creation and tear down. Supported platforms have optimizations for handling output formatting, paging striping, etc.

This higher level design brings increased performance and more ergonomic device interactions – but at the cost of flexibility since the raw protocol is obscured.

So Netmiko trades control in favor of simplification and out-of-the-box productivity for developers.

Advanced Functionality

While I‘ve focused on core functionality till now, both Paramiko and Netmiko support more advanced capabilities that power-users can take advantage of:

Paramiko Advanced Features

• SSH key authentication instead of just username/password auth.
• Asynchronous execution using multi-threading and worker pools for concurrent tasks.
• Proxy jumps to tunnel through intermediate SSH hops to reach endpoints.
• Port forwarding to expose services behind remote hosts.
• Custom interactive terminal sessions beyond just command execution.

Netmiko Advanced Features

• TextFSM integration for structured data extraction from outputs.
• SSH keys for passwordless authentication.
• Asynchronous modes for enabling concurrency and multi-threading.
• Tight integration with network modeling tools like NAPALM and Cisco ConfD.
• Ansible, Puppet, and other automation framework plugins.

These are just some advanced capabilities unlocked in both tools.

Community Support

Given most enterprises rely critically on their network infrastructure, the support ecosystem behind Paramiko and Netmiko plays a major role in adoption decisions.

Paramiko benefits from Python‘s vibrant open source community. GitHub issues see active engagement from maintainers with fixes and enhancements released on a regular cadence. Stack Overflow also contains thousands of questions on Paramiko usage.

However being a more niche library, Netmiko has fostered an ecosystem specifically targeted to network engineers. Kirk Byers moderates a Slack Community with over 2,500 members focused on topics like automation approaches, design patterns, multi-vendor quirks and more. GitHub issues also see quick resolution from a team of contributors.

This category is mostly a wash – both projects sport healthy communities due to their open source nature.

Licensing Considerations

Licensing models present another axis teams evaluate when deciding between open source libraries.

Paramiko uses the GNU GPLv2 license. This "viral" license means derivative works must also be made open source. Its protections err on the side giving community rights to tooling built on Paramiko.

Netmiko uses the permissive MIT license. This allows modify and integrating Netmiko into proprietary network offerings without requiring resulting software also be open sourced. The license favors commercial usage.

There are good arguments around each approach fostering innovation in its own way. Weighing the licenses and resulting impacts on consumption models is an important evaluation aspect when selecting between Paramiko and Netmiko.

When To Use Paramiko vs Netmiko: A Summary

Given the breadth of differences covered, here is quick guidance on when to reach for one library or the other:

Use Paramiko When:

• You want lower level SSH protocol control and access.
• Need advanced workflows like port forwarding or proxy jumps.
• Supporting generic Linux/Unix systems administration automation.

Use Netmiko When:

• Primary focus is network device configuration automation.
• Multi-vendor environments across Cisco, Juniper etc.
• Easy abstraction for sending commands and parsing outputs.
• Moving fast matters – performance is critical.

Of course overlap exists between the tools. But keeping their optimization points in mind helps steer usage towards the right solutions for each job.

Wrapping Up

Paramiko and Netmiko occupy distinct niches in the network automation ecosystem. Hopefully exploring their histories, real-world usage trade-offs, code patterns, architecture, advanced features and community support provides clarity on where each tool shines.

The growth in networks globally shows no signs of slowing. As a result, automation will only increase in importance to help meet reliability and adaptability demands cost-effectively. Understanding foundational libraries like Paramiko and Netmiko for interfacing with gear securely and efficiently gives teams a major edge.

Have you used Paramiko or Netmiko before? Do you have a strong preference or disagree with any of the conclusions presented? Please share your thoughts and experiences below!