Network MCP Server

A Model Context Protocol (MCP) server that lets an AI agent interact with a Cisco IOS-XE network device over SSH. Built in Python with FastMCP and Netmiko.

The server exposes 7 tools (5 read + 2 write), each with strict input validation and clear descriptions so an LLM agent can discover and use them autonomously.

Course: Agent AI & Automation — Sheridan College Author: Ahmed Instructor: Sebastian

Table of contents

1. Lab environment

2. Install

3. Run the server

4. Tools

5. Connect to Claude Desktop

6. Example interactions

7. Permissions required

8. Security notes

9. Troubleshooting

Lab environment

This project targets Cisco's Always-On IOS-XE DevNet Sandbox. It is free, publicly reachable, requires no reservation, and is always up.

Reference: Cisco DevNet — Always-On Sandboxes.

Quick connectivity check from your machine:

ssh admin@sandbox-iosxe-latest-1.cisco.com
# password: C1sco12345

You should land at Router# (or similar) prompt. If this works, the MCP server will work too.

The sandbox is shared. Please keep changes small and non-disruptive (e.g. only edit interface descriptions, don't shut interfaces or change IPs).

Install

Requires Python 3.10+.

# 1. Clone / copy the project
cd network-mcp-server

# 2. Create and activate a virtual environment (recommended)
python -m venv .venv
source .venv/bin/activate    # on Windows: .venv\Scripts\activate

# 3. Install dependencies
pip install -r requirements.txt

Dependencies:

• mcp[cli] — MCP Python SDK (provides FastMCP)

• netmiko — multi-vendor SSH/CLI library

• python-dotenv — loads .env for local dev

Run the server

Option A — standalone (for local testing)

cp .env.example .env
# edit .env if your lab uses different credentials

python server.py

The server runs over stdio, so it waits on stdin for MCP JSON-RPC messages. In practice you won't invoke it by hand — you'll connect Claude Desktop (see below) or the mcp dev CLI.

Option B — interactive dev inspector

mcp dev server.py

This opens the MCP Inspector in your browser where you can list tools and call them manually.

Tools

Read tools

Write tools

All tool outputs are JSON strings so the LLM can reason over structured data. When Netmiko's TextFSM parsers can't handle an output, the server falls back to raw CLI text inside a {"raw": "..."} wrapper.

Connect to Claude Desktop

1. Locate Claude Desktop's config file:

   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

   • Windows: %APPDATA%\Claude\claude_desktop_config.json

   • Linux: ~/.config/Claude/claude_desktop_config.json

2. Merge the block below into the file (use the full absolute path to your server.py):

{
  "mcpServers": {
    "network-mcp-server": {
      "command": "python",
      "args": ["/ABSOLUTE/PATH/TO/network-mcp-server/server.py"],
      "env": {
        "DEVICE_HOST": "sandbox-iosxe-latest-1.cisco.com",
        "DEVICE_PORT": "22",
        "DEVICE_USERNAME": "admin",
        "DEVICE_PASSWORD": "C1sco12345",
        "DEVICE_TYPE": "cisco_xe"
      }
    }
  }
}

A ready-to-copy version lives in claude_desktop_config.example.json.

3. Fully quit and reopen Claude Desktop. (Just closing the window is not enough — it keeps the MCP process alive.)

4. In a new chat, click the 🛠️ / tools icon. You should see network-mcp-server listed with 7 tools.

Example interactions

Once connected, try these prompts:

"What device am I connected to? Give me its hostname, model, and IOS version." The agent will call get_device_info.

"List all interfaces that currently have an IP address assigned." The agent will call get_interfaces and filter the results.

"Show me the default route." The agent will call get_routes and pick the entry with network 0.0.0.0.

"Set the description on GigabitEthernet2 to 'managed by MCP demo', then confirm the change was applied." The agent will call configure_interface_description, then (optionally) get_running_config with section='interface GigabitEthernet2' to double-check.

"Save the running config to startup." The agent will call save_config.

Permissions required

The MCP server needs:

1. Network egress from the host machine to the device's SSH port (TCP/22 by default). On corporate networks you may need a VPN or proxy.

2. A device account with privileged exec rights — the DevNet sandbox's admin account is already enable-level. If you use your own device, the account must be able to enter config t and issue write memory.

3. Local read access to the .env file or equivalent environment variables set by Claude Desktop.

The server does not need root/admin on your workstation.

Security notes

• Credentials are never hardcoded. They come from environment variables (DEVICE_USERNAME, DEVICE_PASSWORD). If any required env var is missing the server refuses to connect and returns a clear error.

• .env is git-ignored. A .env.example (with safe-to-share DevNet sandbox values) is provided instead.

• Input validation on every tool. Interface names, descriptions, and config-section filters are all regex-validated before reaching the device CLI. Shell metacharacters (;, |, backtick, newline, null byte) are rejected.

• Credentials are never exposed as tool arguments. The LLM cannot read, log, or exfiltrate them — it only sees tool outputs.

• Write tools include verification. configure_interface_description reads the config back after applying the change and reports applied: true/false.

• Scope is narrow. The two write tools can only change interface descriptions and save the config. Destructive operations (shutdown, IP-address change, VLAN delete, erase startup-config) are deliberately not exposed.

Troubleshooting

"Missing required environment variable(s)" You forgot to set DEVICE_HOST / DEVICE_USERNAME / DEVICE_PASSWORD. Copy .env.example to .env or set them in Claude Desktop's env block.

"Authentication to failed" Double-check the password. If you changed the sandbox or use a different device, make sure SSH is enabled and the account has privileged-exec access.

"Connection to timed out" Network egress is blocked. Try ssh admin@sandbox-iosxe-latest-1.cisco.com from the same machine. If that hangs too, your firewall/VPN is the issue.

Claude Desktop doesn't show the server after editing the config Fully quit Claude Desktop (not just close the window) and reopen it. On macOS: Cmd+Q. On Windows: right-click tray icon → Quit.

Tool call returns raw text instead of parsed JSON This means Netmiko's TextFSM template didn't match the device output (different IOS version, different platform). The server falls back to raw CLI text in {"raw": "..."}. The agent can still reason over it; it's just not structured.