Packet Tracer MCP Server

Beta — Active development. Some features may be incomplete or change in future versions.

Control Cisco Packet Tracer in real time using natural language through any MCP-compatible AI agent — Claude Code, OpenCode, Cursor, Continue, Cline, and more.

Write prompts like "create a WAN network with OSPF between two sites" and watch the topology build itself live inside Packet Tracer.

How it works

Your AI agent (Claude Code, OpenCode, Cursor, Cline...)
        |
        v  natural language prompt
  MCP Server (Python)  <- stdio transport
        |
        v  generates JavaScript (PTBuilder API)
  Local HTTP server :54321
        |
        v  PTBuilder-MCP auto-polls /next every 500ms
  PTBuilder-MCP (extension running inside PT)
        |
        v  executes live
  Cisco Packet Tracer

Requirements

• Python 3.11+
• Cisco Packet Tracer 8.x
• Builder-MCP.pts installed in PT (see Packet Tracer setup)
• Any MCP-compatible AI agent (Claude Code, OpenCode, Cursor, Cline, Continue, etc.)

Installation

git clone https://github.com/caixax/packet-tracer-mcp
cd packet-tracer-mcp
pip install -e .

Packet Tracer setup

This server requires Builder-MCP.pts, a modified version of PTBuilder that automatically connects to the MCP server when Packet Tracer starts. No manual scripts or copy-pasting needed.

1. Download Builder-MCP.pts from the latest release

2. Open Packet Tracer and go to Extensions > Scripting > Configure PT Script Modules

3. Click Add and select the downloaded Builder-MCP.pts file

4. Make sure it is set to On Startup and click OK

5. Restart Packet Tracer. The bridge starts automatically — no further action needed.

Builder-MCP.pts is a fork of kimmknight/PTBuilder with an added MCP bridge module that auto-polls the MCP server on startup. The original Builder Code Editor functionality is preserved. Source code: github.com/caixax/PTBuilder

Configuration

Most AI coding tools run MCP servers as a subprocess via stdio — no extra setup, just point them at the command. Replace C:/path/to/packet-tracer-mcp with your actual path.

---

Claude Code

cd C:/path/to/packet-tracer-mcp
claude mcp add packet-tracer -- python -m src.server

---

Claude Desktop

# No CLI — edit the config file manually
# Windows: %APPDATA%\Claude\claude_desktop_config.json
# macOS:   ~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "packet-tracer": {
      "command": "python",
      "args": ["-m", "src.server"],
      "cwd": "C:/path/to/packet-tracer-mcp"
    }
  }
}

---

OpenCode

# No CLI — edit the config file manually
# Windows: %APPDATA%\opencode\config.json
# macOS/Linux: ~/.config/opencode/config.json

{
  "mcp": {
    "packet-tracer": {
      "type": "local",
      "command": ["python", "-m", "src.server"],
      "cwd": "C:/path/to/packet-tracer-mcp"
    }
  }
}

---

Cursor

# No CLI — edit the config file manually
# Project-level: .cursor/mcp.json
# Global: ~/.cursor/mcp.json

{
  "mcpServers": {
    "packet-tracer": {
      "command": "python",
      "args": ["-m", "src.server"],
      "cwd": "C:/path/to/packet-tracer-mcp"
    }
  }
}

---

Cline (VS Code)

# No CLI — use the UI
# Cline sidebar > Settings > MCP Servers > Edit MCP Settings

{
  "mcpServers": {
    "packet-tracer": {
      "command": "python",
      "args": ["-m", "src.server"],
      "cwd": "C:/path/to/packet-tracer-mcp"
    }
  }
}

---

Continue

# No CLI — edit the config file manually
# ~/.continue/config.json

{
  "experimental": {
    "modelContextProtocolServers": [
      {
        "transport": {
          "type": "stdio",
          "command": "python",
          "args": ["-m", "src.server"],
          "cwd": "C:/path/to/packet-tracer-mcp"
        }
      }
    ]
  }
}

---

HTTP mode (advanced)

If you want the server running independently so multiple clients can share it, or if your client only supports HTTP/SSE:

python -m src.server --transport http --port 3000
# Server available at http://127.0.0.1:3000/sse

---

Not on the list?

This server follows the MCP specification — it should work with any MCP-compatible client.

Check your client's documentation for how to add a stdio MCP server with a custom command. If you get it working with a client not listed here, feel free to open a PR or issue to add it to this list.

Usage

With Packet Tracer open and the MCP server running, write in Claude:

Create a network with router R1, switch SW1 and two PCs.
Connect them and configure the 192.168.1.0/24 network.

Add a DNS server with IP 192.168.1.10 connected to the switch.
Configure all PCs to use that DNS server.

Create a WAN topology: two routers with a serial link, each with
its own LAN, and configure OSPF area 0 between them.

Available tools

Devices

Tool	Description
pt_add_device	Add a device to the canvas
pt_remove_device	Remove a device from the canvas
pt_list_devices	List devices in the topology
pt_get_device_info	Get detailed info about a device

Connections

Tool	Description
pt_connect	Connect two devices with a cable
pt_disconnect	Remove a cable from a port
pt_list_connections	List all connections

Configuration

Tool	Description
pt_send_commands	Send CLI commands to a router/switch
pt_configure_ip	Configure IP on an interface (shortcut)
pt_configure_pc	Configure IP/DNS on a PC, Laptop or Server
pt_save_config	Save running-config to startup-config

Topology

Tool	Description
pt_apply_template	Apply a predefined topology template
pt_export_topology	Export topology as JSON
pt_validate	Validate network configuration

Device aliases

Alias	Model
router	Cisco 2911
switch	Cisco 2960-24TT
switch-l3	Cisco 3560-24PS
pc	PC-PT
server	Server-PT
laptop	Laptop-PT
tablet	TabletPC-PT
smartphone	SMARTPHONE-PT
phone	Cisco 7960
ap	AccessPoint-PT
wifi	Linksys-WRT300N
firewall	ASA 5506-X
cloud	Cloud-PT
wlc	WLC-3504

Project structure

packet-tracer-mcp/
├── src/
│   ├── server.py              # MCP entry point + resources
│   ├── app.py                 # FastMCP instance + lifespan
│   ├── tools/
│   │   ├── devices.py         # Device tools
│   │   ├── connections.py     # Connection tools
│   │   ├── configuration.py   # CLI configuration tools
│   │   └── topology.py        # Topology and diagnostics
│   ├── bridge/
│   │   ├── pt_connection.py   # HTTP bridge server :54321
│   │   ├── script_builder.py  # PTBuilder JS code generator
│   │   └── command_queue.py   # Serialized async queue
│   └── catalog/
│       ├── devices.json        # Device catalog
│       ├── cables.json         # Cable types
│       └── templates.json      # Topology templates
├── pyproject.toml
└── LICENSE

Troubleshooting

"PTBuilder is not polling"

• Make sure Packet Tracer is open with Builder-MCP.pts installed
• Verify the module is enabled: Extensions > Scripting > Configure PT Script Modules
• Check that it is set to "On Startup"
• Restart Packet Tracer after installing the module

"Port 54321 already in use"

• A previous MCP server process may still be running
• The server automatically cleans up stale processes on startup, but if it fails, restart Packet Tracer and Claude Code

Error "Invalid arguments for IPC call"

• Check the device type is valid (use the aliases from the table above)
• Port names are auto-expanded (Gi0/0 -> GigabitEthernet0/0) but verify they exist on the device model

Error "getPort of null"

• The device was not added successfully before trying to configure it
• Verify pt_add_device succeeded before calling pt_configure_pc

License

MIT