Linux Tools

📖 Description

MCP Linux Tools is an MCP (Model Context Protocol) server that exposes a secure, whitelisted set of operations on a Linux server. It allows AI assistants (such as Cursor) to perform controlled system administration tasks like reading logs, checking service status, managing cron jobs, running WP-CLI commands, and executing sandboxed Python code—all through a uniform API with strict security constraints.

The server runs as a systemd service and communicates over HTTP. All operations are restricted by configurable whitelists (directories, services, WordPress sites). Tools return a uniform response contract {success, data, error, meta}.

✨ Features

• 🔍 Metadata & Discovery – Server info, service whitelist, WordPress allowed sites
• 📂 File Operations – Read files, list directories, head/tail logs (whitelisted paths only)
• ⚙️ System Services – Check status, reload or restart whitelisted services
• 🐍 Python Sandbox – Execute Python code (no network, 8s timeout)
• ⏰ Cron Management – List, add, remove, enable/disable cron jobs
• 🌐 WordPress – WP-CLI runner, cache flush, plugin/user listing, log tailing
• 🗄️ Database – Read-only MySQL queries (dangerous queries blocked)
• 📡 Network – Ping for connectivity testing
• 📌 Git – Safe Git commands (no push/force)

📦 Installation

Requirements

• Python 3.13 or higher
• Root access (for systemctl and crontab)
• Linux system with systemd

Step 1: Clone Repository

# Clone the MCP server repository to /opt/mcp
sudo mkdir -p /opt
cd /opt
sudo git clone https://github.com/gerard-kanters/mcp-linux-tools.git mcp
cd /opt/mcp

Step 2: Create Python Virtual Environment

# Create virtual environment
sudo python3.13 -m venv /opt/mcp/venv

# Install dependencies
sudo /opt/mcp/venv/bin/pip install --upgrade pip
sudo /opt/mcp/venv/bin/pip install -r requirements.txt --break-system-packages

Step 3: Configure

Edit config.json and adjust the settings for your server:

• Set server_type (development or production)
• Set server_ip to your server's IP address
• Set server_name to identify this server
• Configure directory whitelists, service whitelist, and other settings as needed

See the Configuration section below for detailed information about all configuration options.

Step 4: Create Sandbox Directory

sudo mkdir -p /opt/mcp/sandbox
sudo chown root:root /opt/mcp/sandbox
sudo chmod 755 /opt/mcp/sandbox

Step 5: Install Systemd Service

Create a service file: /etc/systemd/system/mcp-linux-tools.service

[Unit]
Description=MCP Linux Tools Server
After=network.target

[Service]
Type=simple
User=root
WorkingDirectory=/opt/mcp
ExecStart=/opt/mcp/venv/bin/python /opt/mcp/server.py
Restart=always
RestartSec=10
StandardOutput=journal
StandardError=journal

# Security settings
NoNewPrivileges=true
PrivateTmp=true
ProtectSystem=strict
ProtectHome=true
ReadWritePaths=/var/log /opt/mcp/sandbox

[Install]
WantedBy=multi-user.target

Enable and start the service:

sudo systemctl daemon-reload
sudo systemctl enable mcp-linux-tools.service
sudo systemctl start mcp-linux-tools.service
sudo systemctl status mcp-linux-tools.service

Step 6: Cursor MCP Configuration

Add to your Cursor MCP configuration (usually ~/.cursor/mcp.json or in Cursor settings):

{
  "mcpServers": {
    "linux-tools": {
      "command": "curl",
      "args": [
        "-X", "POST",
        "http://192.168.1.22:8765/mcp",
        "-H", "Content-Type: application/json",
        "-d", "@-"
      ]
    }
  }
}

Or use direct HTTP transport in Cursor MCP settings with:

• URL: http://192.168.1.22:8765/mcp
• Transport: HTTP

Verification

Check if the server is running:

# Check service status
sudo systemctl status mcp-linux-tools.service

# Check logs
sudo journalctl -u mcp-linux-tools.service -f

# Test HTTP endpoint
curl -X POST http://localhost:8765/mcp -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"tools/list","id":1}'

Installing Updates

To update the MCP server:

cd /opt/mcp
sudo git pull origin main  # or master, depending on your branch
sudo /opt/mcp/venv/bin/pip install -r requirements.txt --break-system-packages
sudo systemctl restart mcp-linux-tools.service

Important: After an update, check if config.json is still correct. New configuration options may have been added.

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🏗️ Architecture

The server follows a modular MCP architecture:

• server.py – Entrypoint: config loading, MCP setup, tool registration, run/retry/signal handling
• config.py – Config loading and validation (fail-fast on missing fields)
• register_tools.py – Central tool registration
• core/ – Core modules:
  • errors.py – Error codes (DENIED_PATH, INVALID_INPUT, COMMAND_BLOCKED, etc.)
  • models.py – Pydantic models for uniform response contract
  • response.py – ok(), err(), err_denied_* helpers
  • security.py – Allowlist and path validation
  • process.py – Subprocess runner
• tools/ – Tool modules per domain:
  • discovery.py, filesystem.py, logs.py, systemd.py
  • python_exec.py, wordpress.py, cron_tools.py, ops.py

All tools return a uniform response contract: {success, data, error, meta}.

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⚙️ Configuration

All configuration is done via config.json in the root of the MCP server directory (/opt/mcp/config.json).

Configuration Sections

Server Identification

• server_type: "development" or "production"
• server_ip: IP address of the server
• server_name: Name for the MCP server

Server Listen (optional)

• server.host: Bind address (default: "0.0.0.0")
• server.port: HTTP port (default: 8765)

Logging

• logging.log_file: Path to log file

Limits

• limits.max_bytes: Maximum file size for reading (default: 524288 = 512KB)
• limits.max_items: Maximum items in directory listings (default: 500)

Python Sandbox

• python.bin: Path to Python interpreter (must be in venv)
• directories.sandbox_cwd: Working directory for Python sandbox

Directory Whitelists

• directories.allowed_read: Directories from which files can be read
• directories.allowed_log: Directories where log files can be read
• directories.allowed_write: Directories where write operations are allowed

Services

• services.whitelist: List of service names that can be managed

WordPress

• wordpress.allowed_sites: Absolute paths to WordPress roots
• wordpress.bin_candidates: Possible locations for WP-CLI binary
• wordpress.log_candidates: Possible locations for WordPress debug logs

Important: After changes to config.json, the service must be restarted:

sudo systemctl restart mcp-linux-tools.service

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🔒 SECURITY OVERVIEW

LINUX SERVER Tools with limited write operations:

✅ WHAT IS ALLOWED:

• READ Files (in allowed directories)
• VIEW Logs (system logs)
• CHECK Service STATUS and RESTART (only whitelisted services)
• EXECUTE Python CODE (sandboxed, no network, 8s timeout)
• MANAGE Cron JOBS (only within MCP-managed section)

❌ WHAT IS NOT ALLOWED:

• Access to arbitrary directories (strict whitelisting)
• Services STOP/START/ENABLE (only restart allowed)
• Sudo/root operations
• Python with network access
• Modifying system crontab outside MCP section

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📂 ALLOWED DIRECTORIES

Directory whitelists are configured in config.json under directories.

Read Access (allowed_read):

Default: /var/log, /etc, /tmp, /opt/, /root/scripts, /var/www

Log Access (allowed_log):

Default: /var/log, /tmp, /var/www

Write Access (allowed_write):

Default: /var/www, /opt/

Note: All directory paths are configurable via config.json. Changes require a service restart.

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🛠️ ALLOWED SERVICES (SERVICE_WHITELIST)

The service whitelist is configured in config.json under services.whitelist. Only services in this list can be checked or restarted.

Default whitelist (as configured in config.json):

• apache2 - Apache webserver
• php8.4-fpm - PHP FastCGI Process Manager
• postfix - Mail server
• opendkim - DomainKeys email authentication
• sshd - SSH daemon
• docker - Container runtime
• memcached - Memory cache daemon
• postgresql - PostgreSQL database server
• odoo - Odoo ERP system

Note: Service names may vary by distribution. Use get_service_whitelist() to query the active whitelist.

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📚 TOOL CATEGORIES

1️⃣ METADATA & DISCOVERY (Read-Only)

• get_server_info() - Server identification (type, IP, name)
• get_service_whitelist() - List of manageable services
• get_wp_allowed_sites() - List of allowed WordPress sites

2️⃣ FILE OPERATIONS

• list_dir(path, pattern, include_files, include_dirs, max_items) - Directory listing (Read-Only)
• read_file(path, max_bytes) - Read file (max 512KB, Read-Only)
• head(path, n) - First N lines (Read-Only)
• tail(path, n) - Last N lines (for logs, Read-Only)
• log_tail(path, n) - Alias for tail (clearer for logs, Read-Only)
• create_directory(path, owner, group, mode, parents) - Create directory ⚠️ (only /var/www and /opt/)
• chmod_file(path, mode) - Change file permissions ⚠️ (only /var/www and /opt/)
• chown_path(path, owner, group) - Change owner ⚠️ (only /var/www and /opt/)

3️⃣ SYSTEM SERVICES

• service_status(name) - Check status (Read-Only)
• reload_service(name) - Reload service via systemctl reload (preferred action, low impact)
• restart_service(name, force_restart) - Service modification: default is reload, use force_restart=True for full restart ⚠️ (Live impact!)

4️⃣ PYTHON EXECUTION

• python_run(code) - Sandboxed Python (no network, 8s timeout)

5️⃣ CRON MANAGEMENT

• cron_list() - View crontab (Read-Only)
• cron_add(job_id, schedule, command) - Add job ⚠️ (Live impact!)
• cron_remove(job_id) - Remove job ⚠️ (Live impact!)
• cron_enable(job_id, enabled) - Enable/disable job ⚠️ (Live impact!)
• cron_next_runs(schedule, n) - Validate schedule (Read-Only)

6️⃣ WORDPRESS OPERATIONS

• wp_cli(site_path, args, as_www_data) - WP-CLI runner for allowed sites
• wp_cache_flush(site_path, as_www_data) - WordPress cache flush
• wp_plugin_list(site_path, as_www_data) - List all plugins (JSON)
• wp_user_list(site_path, as_www_data) - List all users (JSON)
• log_pick_path() - Find WordPress debug log path
• log_tail_ai(n) - Tail WP-log filtered on 'ai-translate:'
• log_tail_flow(n) - Tail WP-log filtered on mapping-flow events
• log_tail_keywords(keywords, n) - Tail WP-log filtered on keywords

7️⃣ DATABASE OPERATIONS

• mysql_query(query, database) - Execute MySQL query (Read-Only, dangerous queries blocked)

8️⃣ NETWORK OPERATIONS

• ping_host(host, count) - Test network connectivity (Read-Only)

9️⃣ GIT OPERATIONS

• git_command(path, command) - Execute Git commands (only safe commands, no push/force)

🔟 SYSTEM COMMANDS

• execute_shell_command(command, user) - Execute shell command ⚠️ (Live impact!)

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💡 USAGE EXAMPLES

Server Info:

{"tool": "get_server_info", "args": {}}

Service Whitelist:

{"tool": "get_service_whitelist", "args": {}}

Service Status:

{"tool": "service_status", "args": {
  "name": "nginx"
}}

Restart Service:

{"tool": "restart_service", "args": {
  "name": "mysql"
}}

View Log File:

{"tool": "log_tail", "args": {
  "path": "/var/log/nginx/error.log",
  "n": 100
}}

Execute Python:

{"tool": "python_run", "args": {
  "code": "import sys; print(sys.version)"
}}

WordPress Cache Flush:

{"tool": "wp_cache_flush", "args": {
  "site_path": "/var/www/netcare.nl"
}}

WordPress Plugin List:

{"tool": "wp_plugin_list", "args": {
  "site_path": "/var/www/netcare.nl"
}}

MySQL Query:

{"tool": "mysql_query", "args": {
  "query": "SHOW DATABASES;",
  "database": ""
}}

Network Ping:

{"tool": "ping_host", "args": {
  "host": "8.8.8.8",
  "count": 4
}}

Git Status:

{"tool": "git_command", "args": {
  "path": "/var/www/example",
  "command": "status"
}}

Add Cron Job:

{"tool": "cron_add", "args": {
  "job_id": "backup_daily",
  "schedule": "0 3 * * *",
  "command": "/usr/bin/backup.sh"
}}

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⚠️ IMPORTANT NOTES FOR LLMs

1. Read-Only Default: Most tools are read-only. Write operations are limited to:

   • reload_service() / restart_service() - Service reload/restart
   • cron_add/remove/enable() - Cron modifications
   • create_directory() - Create directory (only /var/www and /opt/)
   • chmod_file() - Change file permissions (only /var/www and /opt/)
   • chown_path() - Change owner (only /var/www and /opt/)
   • execute_shell_command() - Shell commands (use with caution!)

2. Whitelisting: Everything is whitelisted. Tools return "Denied" if you work outside the whitelist.

3. Service Names: Different distributions use different service names. For example:

   • DNS: systemd-resolved, bind9, or named
   • DHCP: isc-dhcp-server or dhcpd
   • MySQL: mysql, mariadb, or mysqld
   • SMB: smbd or samba

4. Security First:

   • No blind rm -rf possible
   • No arbitrary file writes
   • Python is sandboxed
   • Cron commands must use absolute paths

5. Error Handling – Uniform response contract {success, data, error, meta}:

   • success=true: data contains result, error is null
   • success=false: error contains {code, message, hint}, data is null
   • Error codes: DENIED_PATH, DENIED_SERVICE, DENIED_SITE, INVALID_INPUT, COMMAND_BLOCKED, NOT_FOUND, TIMEOUT, etc.
   • meta: server_type, server_ip, server_name

6. Return Types:

   • Strings for simple output
   • Dicts for structured data (Python, MySQL, etc.)
   • Lists for directories and cron schedules

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🎯 BEST PRACTICES

1. Server identification: Use get_server_info() to verify which server you're working on
2. Check whitelists first: Call get_service_whitelist() before managing services
3. Read-only first: Check status/logs before restarting services
4. Validate cron schedules: Use cron_next_runs() to validate schedules
5. Service names: Check which service name is used on the system
6. Error handling: Always check for "Denied" or {"error": ...} in responses
7. Log locations: Use list_dir() to explore log directories before reading logs
8. Config changes: Always restart the service after changes to config.json

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📊 TESTED & VERIFIED

All tools have been tested and work correctly: ✅ Service status and restart functionality ✅ Log file reading ✅ Python 3.13 execution (sandboxed) ✅ Cron schedule validation ✅ File operations (read-only) ✅ Directory listing

Last Updated: 2026-03-03 Server: Linux (generic) Environment: Production/Development Configuration: Via config.json (no hardcoded values) Architecture: Modular (server.py entrypoint, core/, tools/)