linux-mcp-server 0.1.0a1

MCP server for read-only Linux system administration, diagnostics, and troubleshooting

Linux MCP Server

A Model Context Protocol (MCP) server for read-only Linux system administration, diagnostics, and troubleshooting on RHEL-based systems.

Features

• Read-Only Operations: All tools are strictly read-only for safe diagnostics
• Remote SSH Execution: Execute commands on remote systems via SSH with key-based authentication
• Multi-Host Management: Connect to different remote hosts in the same session
• Comprehensive Diagnostics: System info, services, processes, logs, network, and storage
• Configurable Log Access: Control which log files can be accessed via environment variables
• RHEL/systemd Focused: Optimized for Red Hat Enterprise Linux systems

Architecture Overview

graph TB
    Client["Client Layer<br/>MCP Client (e.g. Claude Desktop)"]

    subgraph Server["MCP Server"]
        FastMCP[FastMCP Server]

        subgraph Tools["Tool Categories"]
            direction LR
            subgraph Row1[" "]
                SystemInfo[System Info]
                Services[Services]
                Processes[Processes]
            end
            subgraph Row2[" "]
            Logs[Logs & Audit]
                Network[Network]
                Storage[Storage]
            end
        end

        Executor[SSH Executor]
        Logger[Audit Logger]
    end

    subgraph Targets["Execution Targets"]
        direction LR
        Local[Local System]
        Remote[Remote Hosts<br/>SSH]
    end

    Client -->|MCP Protocol| FastMCP
    FastMCP --> Tools
    Tools --> Executor
    Executor --> Targets

    FastMCP -.-> Logger
    Executor -.-> Logger

    style Client fill:#4a9eff,stroke:#2563eb,color:#fff
    style FastMCP fill:#f59e0b,stroke:#d97706,color:#fff
    style SystemInfo fill:#64748b,stroke:#475569,color:#fff
    style Services fill:#64748b,stroke:#475569,color:#fff
    style Processes fill:#64748b,stroke:#475569,color:#fff
    style Logs fill:#64748b,stroke:#475569,color:#fff
    style Network fill:#64748b,stroke:#475569,color:#fff
    style Storage fill:#64748b,stroke:#475569,color:#fff
    style Executor fill:#10b981,stroke:#059669,color:#fff
    style Logger fill:#8b5cf6,stroke:#7c3aed,color:#fff
    style Local fill:#eab308,stroke:#ca8a04,color:#fff
    style Remote fill:#eab308,stroke:#ca8a04,color:#fff
    style Row1 fill:none,stroke:none
    style Row2 fill:none,stroke:none

Key Components

• FastMCP Server: Core MCP protocol server handling tool registration and invocation
• Tool Categories: Six categories of read-only diagnostic tools (system info, services, processes, logs, network, storage)
• SSH Executor: Routes commands to local subprocess or remote SSH execution with connection pooling
• Audit Logger: Comprehensive logging in both human-readable and JSON formats with automatic rotation
• Multi-Target Execution: Single server instance can execute commands on local system or multiple remote hosts

Available Tools

System Information

• get_system_info - OS version, kernel, hostname, uptime
• get_cpu_info - CPU details and load averages
• get_memory_info - RAM usage and swap details
• get_disk_usage - Filesystem usage and mount points
• get_hardware_info - Hardware details (CPU architecture, PCI/USB devices, memory hardware)

Service Management

• list_services - List all systemd services with status
• get_service_status - Detailed status of a specific service
• get_service_logs - Recent logs for a specific service

Process Management

• list_processes - Running processes with CPU/memory usage
• get_process_info - Detailed information about a specific process

Logs & Audit

• get_journal_logs - Query systemd journal with filters
• get_audit_logs - Read audit logs (if available)
• read_log_file - Read specific log file (whitelist-controlled)

Network Diagnostics

• get_network_interfaces - Network interface information
• get_network_connections - Active network connections
• get_listening_ports - Ports listening on the system

Storage & Disk Analysis

• list_block_devices - Block devices and partitions
• list_directories_by_size - List directories sorted by size (largest first) with top N limit
• list_directories_by_name - List all directories sorted alphabetically (A-Z or Z-A)
• list_directories_by_modified_date - List all directories sorted by modification date (newest/oldest first)

Installation

Prerequisites

• Python 3.10 or higher
• uv package manager

Setup

1. Clone the repository:

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

2. Create virtual environment and install dependencies:

uv venv
source .venv/bin/activate
uv pip install -e ".[dev]"

Configuration

Configure the server using environment variables:

# Comma-separated list of allowed log file paths
export LINUX_MCP_ALLOWED_LOG_PATHS="/var/log/messages,/var/log/secure,/var/log/audit/audit.log"

# Optional: Set log level (DEBUG, INFO, WARNING, ERROR, CRITICAL)
export LINUX_MCP_LOG_LEVEL="INFO"

# Optional: Custom log directory (default: ~/.local/share/linux-mcp-server/logs/)
export LINUX_MCP_LOG_DIR="/var/log/linux-mcp-server"

# Optional: Log retention in days (default: 10)
export LINUX_MCP_LOG_RETENTION_DAYS="30"

# Optional: Specify SSH private key path (defaults to ~/.ssh/id_ed25519, ~/.ssh/id_rsa, etc.)
export LINUX_MCP_SSH_KEY_PATH="/path/to/your/private/key"

Audit Logging

The server includes comprehensive audit logging for all operations:

Features:

• Dual Format: Logs written in both human-readable text and JSON formats
• Daily Rotation: Automatic log rotation at midnight
• Configurable Retention: Keep logs for a specified number of days (default: 10)
• Tiered Verbosity: INFO for operations, DEBUG for detailed diagnostics
• Sanitization: Automatic redaction of sensitive data (passwords, tokens, API keys)

Log Files:

• Human-readable: ~/.local/share/linux-mcp-server/logs/server.log
• JSON format: ~/.local/share/linux-mcp-server/logs/server.json
• Rotated files: server.log.YYYY-MM-DD and server.json.YYYY-MM-DD

What Gets Logged:

• Server startup and shutdown
• All tool invocations with parameters (sanitized)
• Tool execution time and completion status
• SSH connections (success/failure)
• Remote command execution
• Error conditions with full context

Log Levels:

• DEBUG: Detailed flow, connection reuse, function entry/exit, timing details
• INFO: Tool calls, command executions, connection events, operation results
• WARNING: Authentication failures, retryable errors, missing optional data
• ERROR: Failed operations, exceptions, connection failures
• CRITICAL: Server startup/shutdown failures, unrecoverable errors

Example Log Entries:

# Human-readable format (server.log)
2025-10-10 14:23:45.123 | INFO | server | TOOL_CALL: list_services | host=server1.example.com | username=admin | execution_mode=remote
2025-10-10 14:23:45.234 | INFO | ssh_executor | SSH_CONNECT: [e-mail] | status=success
2025-10-10 14:23:45.345 | INFO | ssh_executor | REMOTE_EXEC: systemctl list-units --type=service | host=server1.example.com | exit_code=0
2025-10-10 14:23:45.456 | INFO | server | TOOL_COMPLETE: list_services | status=success | duration=0.333s

# JSON format (server.json)
{"timestamp": "2025-10-10T14:23:45.123Z", "level": "INFO", "logger": "server", "message": "TOOL_CALL: list_services", "event": "TOOL_CALL", "tool": "list_services", "host": "server1.example.com", "username": "admin", "execution_mode": "remote"}

Remote SSH Execution

All tools support optional host and username parameters for remote execution via SSH:

• Authentication: SSH key-based authentication only (no password support)
• Key Discovery: Automatically discovers SSH keys from ~/.ssh/ or use LINUX_MCP_SSH_KEY_PATH
• Connection Pooling: Reuses SSH connections for efficiency
• Multi-Host: Each tool call can target a different remote host

Requirements:

• SSH key-based authentication must be configured on remote hosts
• Remote user must have appropriate permissions for diagnostic commands

Example Usage:

# Local execution
await list_services()

# Remote execution
await list_services(host="server1.example.com", username="admin")

# Different host in same session
await get_service_status("nginx", host="server2.example.com", username="sysadmin")

Usage

Running the Server

You can run the server in multiple ways:

Using uv run (recommended for development):

uv run linux-mcp-server

Using uvx (recommended for one-off execution without installation):

uvx --from /path/to/linux-mcp-server linux-mcp-server

Traditional Python module execution:

python -m linux_mcp_server

Using with Claude Desktop

Add to your Claude Desktop configuration (~/Library/Application Support/Claude/claude_desktop_config.json on macOS):

Option 1: Using uv run (simpler):

{
  "mcpServers": {
    "linux-diagnostics": {
      "command": "uv",
      "args": [
        "--directory",
        "/path/to/linux-mcp-server",
        "run",
        "linux-mcp-server"
      ],
      "env": {
        "LINUX_MCP_ALLOWED_LOG_PATHS": "/var/log/messages,/var/log/secure,/var/log/audit/audit.log"
      }
    }
  }
}

Option 2: Using uvx (from local directory):

{
  "mcpServers": {
    "linux-diagnostics": {
      "command": "uvx",
      "args": [
        "--from",
        "/path/to/linux-mcp-server",
        "linux-mcp-server"
      ],
      "env": {
        "LINUX_MCP_ALLOWED_LOG_PATHS": "/var/log/messages,/var/log/secure,/var/log/audit/audit.log"
      }
    }
  }
}

Development

Running Tests

pytest

Running Tests with Coverage

pytest --cov=src --cov-report=html

Security Considerations

• All operations are read-only
• Log file access is controlled via whitelist (LINUX_MCP_ALLOWED_LOG_PATHS)
• SSH key-based authentication only - no password support
• SSH host key verification is disabled for flexibility (use with caution)
• No arbitrary command execution
• Input validation on all parameters
• Requires appropriate system permissions for diagnostics
• Remote user needs proper sudo/permissions for privileged commands