MCP Server Junos (Juniper Devices)

Junos MCP Server (mcp-server-junos)

Overview

The mcp-server-junos project provides MCP tools for viewing operational state and changing configuraton of Juniper Networks devices with Junos operating system. it uses Juniper's junos-eznc Python SDK and FastMCP.

Tools

• get_fact: Retrieve basic information about the device, such as OS version and model.
• show_command: Execute any specified show command on the device and return the output. It can be used to retrieve device configuration and execute ping command.
• apply_config: Load and commit configuration changes to the device in both set and junos (curly brackets) formats.
• list_devices: Retrieve the list of locally configured devices on the MCP server. The list include device name and IP address for remote access.

Installation

1. Clone the repository:

   git clone <repository-url>
   cd mcp-server-junos
   

Running as a standalone application

2. Install the required dependencies:

   pip install -r requirements.txt
   

3. Rename example config file config.example.yml to config.yml

   mv config.example.yml config.yml
   

Running as a docker container

NOTE: If you want to include the configuration file in the docker image, please configure it in advance before building the container image. Otherwise, you can provide global access parameters into the container using Environment Variables (example in Usage section)

2. Rename example config file config.example.yml to config.yml and configure it accordingly, before

   mv config.example.yml config.yml
   

3. Build docker container image

   docker build -t mcp-server-junos .
   

Configuration

The expected configuration file is named config.yml and it should be located in the root directory. The supplied example config file config.example.yml can be used as a starting point

mv config.example.yml config.yml

If Environment variables are used, they will take precedence over configuration file parameters.

Global server configuration

Using config file:

global:
  # To listen on all available interfaces use "0.0.0.0"
  server_host: 127.0.0.1
  server_port: 10008
  # Possible values: "sse" or "streamable-http"
  server_transport: "streamable-http"

Using Environment variables:

MCP_SERVER_JUNOS_HOST="127.0.0.1"
MCP_SERVER_JUNOS_PORT=10008
MCP_SERVER_JUNOS_TRANSPORT="streamable-http"
LOG_LEVEL="INFO"

Devices inventory

Using config file:

Configuration file key devices contains the dictionary of the device names with their respective access configuration.

• device_name: Name of the device
  • host: IP address for access
  • user: Username for access
  • passwd: Password for access
  • port: TCP port for NETCONF/SSH access

Example:

access: 

  default:
    user: "admin"
    passwd: "admin@123"
    port: 830

  test: &test
    user: "admin"
    passwd: "admin@123"
    port: 830

devices:

  r1:
    host: 172.20.20.2
    user: "admin"
    passwd: "admin@123"
    port: 830

  r2:
    host: 172.20.20.3
    <<: *test

Default access parameters can be specified for devices which are not explicitly configured in the configuration file. Those can be used through exposed MCP tools by supplying IP address in the host argument.

• First preference are environment variables:

  MCP_SERVER_JUNOS_ACCESS_DEFAULT_USER="admin"
  MCP_SERVER_JUNOS_ACCESS_DEFAULT_PASSWD="admin"
  MCP_SERVER_JUNOS_ACCESS_DEFAULT_PORT=830
  

• Second preference is config file:

  access:
    default:
      user: "admin"
      passwd: "admin"
      port: 830
  

Usage

Running as a standalone application

To use the MCP server, run the file:

python mcp_server_junos.py

• The MCP server exposes HTTP SSE interface on configurable port (default 10008) and IPs
• The URL for connecting locally to MCP server over transport SSE would be: http://127.0.0.1:10008/sse
• The URL for connecting locally to MCP server over transport Streamable HTTP would be: http://127.0.0.1:10008/mcp/

Running as a docker container

When running as a docker container, user can supply global configuration through Environment variables and no configuration file. Access to any device would use those supplied access credentials.

Other option is building a docker image with the configuration file config.yml or mounting it to the container as a volume to /mcp-server-junos/config.yml path.

docker run -d \
  --net=host \
  --name mcp-server-junos \
  -e MCP_SERVER_JUNOS_ACCESS_DEFAULT_USER="admin" \
  -e MCP_SERVER_JUNOS_ACCESS_DEFAULT_PASSWD="admin@123" \
  -e MCP_SERVER_JUNOS_ACCESS_DEFAULT_PORT=830 \
  -e MCP_SERVER_JUNOS_HOST="127.0.0.1" \
  -e MCP_SERVER_JUNOS_PORT=10008 \
  -e MCP_SERVER_JUNOS_TRANSPORT="streamable-http" \
  mcp-server-junos:latest

Tests

Tested with Github Copilot and VS Code (v1.100.2) as MCP client using Streamable HTTP and SSE.

• various show commands
• basic device configuration
• ping between devices

NOTE: Streamable HTTP transport for MCP servers in VS Code is supported from v1.100. Older versions support SSE transport.

License

The project is licensed under the MIT License.