junos-mcp-server

A Model Context Protocol (MCP) server for Juniper Junos devices that enables LLM interactions with network equipment.

Table of Contents

• junos-mcp-server

  • Table of Contents

  • Important Security Notice

    • Security Requirements

    • Security Best Practices

  • Important Configuration Notice

  • Getting Started

    • Running with uv

  • Start Junos MCP Server

  • Configuration

    • Config for Claude Desktop (stdio transport)

    • Config for Claude Desktop (using uv)

    • Config for Claude Desktop (Docker container)

  • Docker Usage

    • Build Docker Container

    • Running with Default Settings

    • Overriding Default Arguments

  • Junos Device Configuration

  • Dynamic Device Management with Elicitation

    • Elicitation Compatibility Notice

    • The

      • How It Works

      • Security Note

      • Example Usage

      • SSH Key Requirements

      • Limitations

  • VSCode + GitHub Copilot Integration

    • Start Your Server

    • Point to This URL in Your VSCode Config

  • Authentication for MCP Server Access

    • Authentication Behavior

    • Token Management

      • Generate a New Token

      • List All Tokens

      • Show Token Value (Recovery)

      • Revoke a Token

    • Server Authentication Status

    • Client Configuration with Authentication

      • VSCode Configuration with Token

      • Testing with curl

      • Docker with Authentication

    • Security Best Practices

    • Token File Format

  • Using MCP Server with Juniper Cloud-Native Router (JCNR)

  • Developer Guide

    • Architecture Overview

    • How Tools Work

    • Adding a New Tool

      • Step 1: Create a Handler Function

      • Step 2: Register the Handler

      • Step 3: Define Tool Metadata

    • Example: Creating a BGP Neighbors Tool

    • Using Elicitation in Tools

    • Best Practices for Tool Development

    • Using PyEZ for Advanced Operations

    • Testing Your Tools

    • Debugging Tips

Important Security Notice

Warning: This server enables LLM access to your network infrastructure. Please review these security considerations carefully.

Security Requirements

• Corporate Policy Compliance: Only use this server if your company's policy allows sending data of Junos devices to LLM services.

• Server Security: Always secure your Junos MCP server before deployment in production environments.

• Authentication: Do not use password authentication for production deployments. We strongly recommend using SSH key-based authentication for enhanced security.

• Deployment Strategy: Until your MCP server is properly secured, only deploy locally for testing purposes. Do not deploy remote servers in production without proper security measures.

Security Best Practices

• Use SSH key authentication instead of passwords

• Implement proper network access controls

• Monitor and log all MCP server activities

• Regular security audits and updates

• Follow your organization's security policies

Important Configuration Notice

Warning: The Junos MCP server supports configuration changes, but please ensure you only use this functionality when you want LLM-generated configurations to be loaded and committed on your Junos router.

Always review the configuration being generated by the LLM and only allow tool execution if it's the correct configuration for your use case.

Getting Started

Get the code.

Running with uv

If you're using uv, you can run the server directly:

Start Junos MCP Server

Junos MCP server supports both streamable-http and stdio transport. Do not use --host with stdio transport.

Configuration

Config for Claude Desktop (stdio transport)

Config for Claude Desktop (using uv)

Note: Please provide absolute path for jmcp.py and devices.json file.

Config for Claude Desktop (Docker container)

Docker Usage

Build Docker Container

Running with Default Settings

By default, the Docker container runs with stdio transport:

This uses the default command: python jmcp.py -f /app/config/devices.json -t stdio

Overriding Default Arguments

You can override any arguments by specifying the full command:

For stdio transport:

For streamable-http transport:

For streamable-http with custom port:

Note:

• Always mount your device configuration file using -v /path/to/your/devices.json:/app/config/devices.json

• For streamable-http transport, expose the port using -p host_port:container_port

• Mount any SSH private key files if using key-based authentication (e.g., -v /path/to/key.pem:/app/config/key.pem)

Build docker container for Junos MCP Server

Note: Mount your config file devices.json and mount any other files, in my case I am using pem file for ssh priv key authentication so I am also mounting vsrx_keypair.pem

Junos Device Configuration

Junos MCP server supports both password based auth as well as SSH key based authentication (See first 2 routers configs [router-1, router-2]).

Junos MCP server also provides support for ProxyCommand. (See last 2 routers configs [router-3, router-4]), which enables you to access a target device through an intermediary host that supports netcat. This is useful when you can only log in to the target device through the intermediate host (jumphost).

This is an example of an SSH config file being used .ssh/config_jumphost:

Note #1: Port value should be an integer (typically 22 for SSH).

Note #2: IdentityFile recommendation use full path (e.g /home/user/.ssh/id_rsa_claude rather than ~/.ssh/id_rsa_claude).

Dynamic Device Management with Elicitation

Elicitation Compatibility Notice

Important: The elicitation feature currently only works with VSCode (using streamable-http transport). Claude Desktop does not yet support elicitation, so the add_device tool will not work with Claude Desktop.

The add_device Tool

The Junos MCP server includes a powerful add_device tool that allows you to dynamically add new Junos devices without modifying the configuration file. This tool uses MCP's elicitation feature to interactively collect device information.

How It Works

When you use the add_device tool, it will interactively ask for:

1. Device Name: A unique identifier for your device (e.g., "router1-east")

2. IP Address: The device's IP address

3. SSH Port: The SSH port (defaults to 22)

4. Username: The username for authentication

5. SSH Key Path: The path to the SSH private key file on the MCP server

The tool validates each input:

• Device names must be unique

• IP addresses must be valid

• SSH key files must exist and be readable

• Optional connection test before adding the device

Security Note

The add_device tool only supports SSH key authentication. Password authentication has been disabled for security reasons and because VSCode's elicitation UI doesn't properly mask password fields.

Example Usage

In VSCode with GitHub Copilot:

The tool will then guide you through the process:

1. Enter device name: vsrx-lab1

2. Enter IP address: 10.0.1.100

3. Enter SSH port: 22 (or press Enter for default)

4. Enter username: admin

5. Enter SSH key path: /home/user/.ssh/junos_key.pem

6. Confirm and optionally test connection

After successful addition, the device is immediately available for use with all other Junos MCP tools.

SSH Key Requirements

• The SSH private key file must exist on the MCP server filesystem

• The file must be readable by the process running the MCP server

• For Docker deployments, mount the SSH key file into the container

Example Docker mount:

Limitations

• VSCode Only: Elicitation is not supported in Claude Desktop

• SSH Key Only: No password authentication support

• No Persistence: Added devices are only stored in memory; they will be lost when the server restarts

• Timeout: Users have 5 minutes to respond to each prompt

For Claude Desktop users, devices must still be configured in the devices.json file as described in the Junos device config section.

VSCode + GitHub Copilot Integration

Start Your Server

Point to This URL in Your VSCode Config

Note: You can use VSCode's Cmd+Shift+P to configure MCP server.

Authentication for MCP Server Access

The Junos MCP server supports token-based authentication for secure client access when using streamable-http transport. This prevents unauthorized access to your network infrastructure.

Authentication Behavior

• stdio transport (Claude Desktop): No authentication required - secure by design as it runs locally

• streamable-http transport (VSCode, web clients): Token-based authentication available

Token Management

The server includes a dedicated token management CLI tool: jmcp_token_manager.py

Generate a New Token

List All Tokens

Show Token Value (Recovery)

Revoke a Token

Server Authentication Status

The server automatically detects and enables authentication based on the presence of tokens:

With tokens configured:

Without tokens configured:

Client Configuration with Authentication

VSCode Configuration with Token

Testing with curl

Note: MCP streamable-http requires the Accept: application/json, text/event-stream header.

Docker with Authentication

When using Docker, mount the .tokens file to enable authentication:

Security Best Practices

1. Token Security:

   • Store tokens securely (password managers, environment variables)

   • Use descriptive token IDs for easy management

   • Regularly rotate tokens by revoking old ones and generating new ones

   • Never commit tokens to version control

2. Access Control:

   • Generate separate tokens for different clients/environments

   • Revoke tokens immediately when no longer needed

   • Monitor server logs for unauthorized access attempts

3. Network Security:

   • Run streamable-http server behind reverse proxy with HTTPS in production

   • Use firewall rules to restrict access to MCP server port

   • Consider VPN access for remote clients

Token File Format

The .tokens file stores tokens in JSON format:

Important: Keep this file secure and don't commit it to version control.

Using MCP Server with Juniper Cloud-Native Router (JCNR)

JCNR is a cloud native router that runs on various cloud environments. One can use this MCP server with JCNR as well by following the steps given below. Please refer to JCNR documentation for more details on configuration.

• Configure SSH access in JCNR on a desired port other than 22. This is required because, JCNR runs as a container on shared operating system. Running SSH on default port is not recommended. By default SSH is enabled on port 24. But, it is preferred to change this to desired port depending on your networking needs.

• Enable authentication method for SSH. JCNR supports SSH key and password based authentications.

• Enable Netconf over SSH. This is enabled by default.

Developer Guide

This section explains the architecture of the Junos MCP server and how to extend it with new tools.

Architecture Overview

The Junos MCP server uses the Model Context Protocol (MCP) to enable LLMs to interact with Juniper network devices. The server architecture consists of:

1. MCP Server Core (jmcp.py): Handles MCP protocol communication

2. Tool Handlers: Individual functions that implement specific network operations

3. Tool Registry: Maps tool names to their handler functions

4. Transport Layer: Supports stdio (Claude Desktop) and streamable-http (VSCode)

How Tools Work

Each tool in the MCP server follows this flow:

Adding a New Tool

Adding a new tool is a simple 3-step process:

Step 1: Create a Handler Function

Create an async handler function in jmcp.py (before the TOOL_HANDLERS dictionary):

Step 2: Register the Handler

Add your handler to the TOOL_HANDLERS dictionary (around line 330):

Step 3: Define Tool Metadata

Add the tool definition to the list_tools() method (around line 410):

Example: Creating a BGP Neighbors Tool

Here's a complete example of adding a tool to show BGP neighbors:

Using Elicitation in Tools

The MCP server supports elicitation for interactive data collection. To use elicitation in your tools:

Note: Elicitation currently only works with VSCode (streamable-http transport). Claude Desktop does not support elicitation yet.

Best Practices for Tool Development

1. Error Handling: Always handle connection errors and invalid inputs gracefully

2. Logging: Use the global log logger for debugging

3. Validation: Check if router exists before attempting operations

4. Documentation: Write clear descriptions for tools and parameters

5. Timeouts: Support configurable timeouts for long-running operations

6. Return Format: Always return list[types.ContentBlock] with text content

7. Elicitation: Use elicitation for interactive data collection when needed

8. Context Parameter: Include context: Context parameter if using elicitation

Using PyEZ for Advanced Operations

For operations beyond CLI commands, use PyEZ directly:

Testing Your Tools

1. Unit Testing: Test handler functions with mock arguments

2. Integration Testing: Test with actual Junos devices or vSRX

3. Error Cases: Test with invalid routers, network failures, etc.

Example test:

Debugging Tips

1. Enable debug logging to see detailed execution:

   logging.basicConfig(level=logging.DEBUG)

2. Use the stdio transport for easier debugging:

   python jmcp.py -f devices.json -t stdio

3. Test individual commands manually:

   result = _run_junos_cli_command("router-1", "show version") print(result)