MCP Standalone — ChatGPT VPS Tools

Standalone MCP server for ChatGPT (and Claude/Cursor) — exposes VPS tools via OAuth 2.1 + PKCE S256, long-horizon ready with exec_start/poll.

Forked pattern from mso/lib/mcp — no Next.js, no database, just Fastify + ~/.mcp-standalone/mcp.json (sha256 only, atomic 0600).

Features

• OAuth 2.1 PKCE S256 only (plain rejected), code_verifier 43-128, isAllowedRedirect https-only, timingSafeEqual

• Discovery: /.well-known/oauth-authorization-server (RFC 8414) + /.well-known/oauth-protected-resource (RFC 9728) + /.well-known/openid-configuration fallback + /.well-known/oauth-protected-resource/mcp variants

• DCR: POST /oauth/register (RFC 7591) → 201 with client_id, grant_types, etc.

• Tools (16): fs_list, fs_read, fs_search, fs_usage, sys_stats, sys_processes (read) + fs_write, fs_mkdir, fs_delete, fs_move, fs_copy (write) + exec_run, exec_start, exec_status, exec_output, exec_wait (exec, long-horizon)

• Long-horizon: exec_start returns <500ms {job_id, pid}, poll exec_status/output/wait until completed — never exec_run for >30s tasks

• Jail: MCP_FS_READ_ROOTS / WRITE_ROOTS (realpath), denylist ~/.ssh, ~/.mcp-standalone, ~/.mso, etc., catastrophic filter (rm -rf /, fork bomb → 126)

Related MCP server: remote-admin-mcp

Quick Start

cp .env.example .env  # fill MCP_SESSION_SECRET (openssl rand -hex 32), MCP_LOGIN_PASSWORD, etc.
npm install
npm start  # or systemd: mcp-standalone.service → :8790

.env:

PORT=8790
HOST=127.0.0.1
MCP_BASE_URL=https://mcp.brain.biz.id
MCP_SESSION_SECRET=...
MCP_LOGIN_PASSWORD=...
MCP_FS_READ_ROOTS=~:~/projects:~/bridgemind:~/HERMES-OC
MCP_FS_WRITE_ROOTS=~:~/projects:~/bridgemind:~/HERMES-OC
MCP_MAX_SCOPE=exec
OAUTH_CLIENT_ID=chatgpt-mcp-xxxx  # optional, empty = allow DCR any
MCP_STORE=~/.mcp-standalone/mcp.json

Cloudflare Tunnel

# ~/.cloudflared/config.yml
- hostname: mcp.brain.biz.id
  service: http://localhost:8790

cloudflared tunnel route dns gendis-shine mcp.brain.biz.id
sudo systemctl restart cloudflared-tunnel

ChatGPT Connectors

• MCP Server URL: https://mcp.brain.biz.id/mcp

• Auth: OAuth → https://mcp.brain.biz.id/oauth/authorize + https://mcp.brain.biz.id/oauth/token

• Client ID: chatgpt-mcp-... or leave empty for DCR

• Scope: exec

Verify:

curl https://mcp.brain.biz.id/.well-known/oauth-authorization-server | jq
curl https://mcp.brain.biz.id/health

Systemd

sudo cp mcp-standalone.service /etc/systemd/system/
sudo systemctl enable --now mcp-standalone

License

MIT