mcp-bulkhead

⚠️ WARNING: Do not run this on anything you care about. Development testing only. ⚠️

An MCP server that gives Claude Desktop the ability to run PowerShell commands on your local Windows machine. It includes a configurable command blacklist — a simple safety you can adjust or removed (if you like running with knives).

Quick Start (Claude Desktop)

Add to %APPDATA%\Claude\claude_desktop_config.json:

{
  "mcpServers": {
    "mcp-bulkhead": {
      "command": "cmd",
      "args": ["/c", "npx", "-y", "mcp-bulkhead"],
      "env": {
        "MCP_BULKHEAD_CONFIG": "C:\\path\\to\\bulkhead.json"
      }
    }
  }
}

The cmd /c wrapper is required for Claude Desktop to launch npx-based MCP servers on Windows.

MCP_BULKHEAD_CONFIG is optional — if omitted, the server uses built-in defaults.

Configuration

Create a JSON config file and point MCP_BULKHEAD_CONFIG to it:

{
  "workingDirectory": "C:\\dev",
  "blacklist": [
    "Remove-Item", "rm", "rmdir", "del", "rd",
    "Format-Volume", "format", "Clear-Disk",
    "Set-Acl", "chmod", "chown", "icacls",
    "Start-Process", "sudo", "su", "runas",
    "Stop-Computer", "Restart-Computer", "shutdown", "reboot",
    "reg", "regedit"
  ],
  "timeoutSeconds": 30,
  "audit": { "enabled": true }
}

| Field | Type | Default | Description | |-------|------|---------|-------------| | workingDirectory | string | process cwd | Absolute path used as cwd for execution | | blacklist | string[] | see above | Commands blocked from execution | | timeoutSeconds | number | 30 | Max seconds per command before kill | | audit.enabled | boolean | true | Log every command execution as JSON lines | | audit.file | string | bulkhead.log next to config file | File path to append audit logs to. Set to "" to disable file logging. |

All fields are optional. Omitted fields use defaults. The blacklist is fully yours to control — add, remove, or empty it.

Command rules

• One command per call. Chain operators (;, &&, ||) are rejected.
• Pipes are allowed. Each pipe segment is checked against the blacklist.

Get-Process | Select-Object Name     # allowed — pipe
Get-Process; Stop-Service foo        # blocked — chain operator
Get-Process | Remove-Item            # blocked — Remove-Item in second segment

Features (configurable in JSON)

1. Blacklist — blocks dangerous commands. Can be emptied.
2. Working directory — sets the default execution context. Does not restrict access to other paths.
3. Timeout — kills long-running commands.
4. Audit log — JSON lines to stderr and/or a file. Can be disabled.

Development

git clone https://github.com/CarolinaTech-io/mcp-bulkhead.git
cd mcp-bulkhead
npm install
npm run build
npm test

Test with the MCP Inspector:

npx @modelcontextprotocol/inspector node build/index.js

License

MIT