Filesystem: Rock-Solid Security, Granular Access

Filesystem: Lock down data with granular access controls and rock-solid security—give teams flexible power without compromising safety. Your rules, your peace of mind.

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About Filesystem

What is Filesystem: Rock-Solid Security, Granular Access?

At its core, this Node.js server implements the Model Context Protocol (MCP) to enforce strict file system boundaries while enabling precise control over data operations. Unlike generic file servers, it operates within a sandbox of explicitly whitelisted directories specified at runtime—think of it as a security-conscious API gateway for file I/O. This design ensures no unauthorized access beyond pre-approved paths, even if malicious inputs slip through upper layers.

How to Use Filesystem: Rock-Solid Security, Granular Access?

Deployment follows three key steps: 1) Define allowed directories via command-line arguments 2) Configure clients to reference the "file://system" resource endpoint 3) Leverage the API's safety-first tools. For example, to restrict development environments, start the server with: node fs-server /var/safe-data /mnt/secure. Client applications must then use the granularAccessToken() method before performing operations, ensuring requests stay within the configured zones.

Filesystem Features

Key Features of Filesystem: Rock-Solid Security, Granular Access?

Path-based lockdown: Operations are confined to pre-configured directories, preventing traversal attacks
Context-aware editing: The edit_file() method enforces checksum validation and version tracking to detect tampering
Automated audit trails: All read/write operations are logged with timestamps and client metadata by default
Role-based access profiles: Assign permissions via JSON policies specifying allowed methods and path patterns

Use Cases of Filesystem: Rock-Solid Security, Granular Access?

Common scenarios include:

Securing CI/CD pipelines by isolating build artifacts in restricted directories
Managing multi-tenant SaaS environments with per-customer file boundaries
Automating compliance reporting through built-in audit APIs
Legacy system integration where existing apps can't be modified to use modern security frameworks

Filesystem FAQ

FAQ from Filesystem: Rock-Solid Security, Granular Access?

How does path validation work?: Uses a combination of realpath() checks and regex pattern matching against the configured allowlist, rejecting relative path components that could bypass restrictions.
Can I override security settings programmatically?: Explicitly prohibited through the --no-override flag. Policy enforcement is hard-coded to prevent runtime bypass attempts.
What happens if a file is edited outside the allowed directories?: Returns standardized 403-SANDBOX_BREACH errors with path context, while triggering incident alerts via configured monitoring hooks.
Does this support encrypted file storage?: Acts as a control layer atop any storage, but integrates with encryption middleware through the storageAdapter configuration option.

Content

Filesystem MCP Server

Node.js server implementing Model Context Protocol (MCP) for filesystem operations.

Features

Read/write files
Create/list/delete directories
Move files/directories
Search files
Get file metadata

Note: The server will only allow operations within directories specified via args.

API

Resources

file://system: File system operations interface

Tools

read_file
- Read complete contents of a file
- Input: path (string)
- Reads complete file contents with UTF-8 encoding
read_multiple_files
- Read multiple files simultaneously
- Input: paths (string[])
- Failed reads won't stop the entire operation
write_file
- Create new file or overwrite existing (exercise caution with this)
- Inputs:
  - path (string): File location
  - content (string): File content
edit_file
- Make selective edits using advanced pattern matching and formatting
- Features:
  - Line-based and multi-line content matching
  - Whitespace normalization with indentation preservation
  - Fuzzy matching with confidence scoring
  - Multiple simultaneous edits with correct positioning
  - Indentation style detection and preservation
  - Git-style diff output with context
  - Preview changes with dry run mode
  - Failed match debugging with confidence scores
- Inputs:
  - path (string): File to edit
  - edits (array): List of edit operations
    - oldText (string): Text to search for (can be substring)
    - newText (string): Text to replace with
  - dryRun (boolean): Preview changes without applying (default: false)
  - options (object): Optional formatting settings
    - preserveIndentation (boolean): Keep existing indentation (default: true)
    - normalizeWhitespace (boolean): Normalize spaces while preserving structure (default: true)
    - partialMatch (boolean): Enable fuzzy matching (default: true)
- Returns detailed diff and match information for dry runs, otherwise applies changes
- Best Practice: Always use dryRun first to preview changes before applying them
create_directory
- Create new directory or ensure it exists
- Input: path (string)
- Creates parent directories if needed
- Succeeds silently if directory exists
list_directory
- List directory contents with [FILE] or [DIR] prefixes
- Input: path (string)
move_file
- Move or rename files and directories
- Inputs:
  - source (string)
  - destination (string)
- Fails if destination exists
search_files
- Recursively search for files/directories
- Inputs:
  - path (string): Starting directory
  - pattern (string): Search pattern
  - excludePatterns (string[]): Exclude any patterns. Glob formats are supported.
- Case-insensitive matching
- Returns full paths to matches
get_file_info
- Get detailed file/directory metadata
- Input: path (string)
- Returns:
  - Size
  - Creation time
  - Modified time
  - Access time
  - Type (file/directory)
  - Permissions
list_allowed_directories
- List all directories the server is allowed to access
- No input required
- Returns:
  - Directories that this server can read/write from

Usage with Claude Desktop

Add this to your claude_desktop_config.json: json { "mcpServers": { "filesystem": { "command": "npx", "args": [ "-y", "@modelcontextprotocol/server-filesystem", "/Users/username/Desktop", "/path/to/other/allowed/dir" ] } } }

License

This MCP server is licensed under the MIT License. This means you are free to use, modify, and distribute the software, subject to the terms and conditions of the MIT License. For more details, please see the LICENSE file in the project repository.