Multi-Hoster-Upload/docs/remote-diagnostics-setup.md
Administrator cfd5ca07ec chore(gateway/tooling): verify harnesses, Windows token ACL, ESM lint, honest transport docs
Repo-side hardening and tooling from the intensive test round (none of this ships
in the app installer).

- gateway: registry.json (holds bearer tokens) now gets a best-effort owner-only
  NTFS ACL on Windows via `icacls /inheritance:r /grant:r <user>:F` (the chmod
  0600 is a no-op on NTFS); verified the file ends up <user>:(F) only.
- gateway: connect_server now reads the app version from the real get_system_info
  shape (data.app.version / data.agent.version), so "connected to vX.Y.Z" works.
- gateway: read_log tool description documents grep as a case-insensitive substring
  filter with "|" alternation (not a regex), matching the agent-side change.
- gateway: standalone verification harnesses moved to gateway/verify/ (so
  `node --test` only sweeps real unit tests) and exposed via `npm run verify`:
  e2e-verify, integration-mcp (live gateway-MCP <-> agent, all 14 tools), and
  adversarial-probe (redaction fuzz + ReDoS + lockout). `npm test` runs the units.
- eslint: gateway/** now lints as ESM (sourceType module) via a dedicated block;
  global ignores fixed so `eslint .` is clean across the whole project (0 errors).
- docs/remote-diagnostics-setup.md: made the transport story honest — the agent
  speaks plaintext ws:// over enforced loopback; the SSH/WireGuard tunnel is the
  ONLY confidentiality layer (wss/TLS + cert-pin is a documented future mode, not
  active). Removed the stale "bind to a LAN/VPN IP" guidance (loopback is enforced).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-19 18:41:21 +02:00

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5.4 KiB
Markdown

# Remote Diagnostics Setup (read-only)
This guide explains how to let Claude Code run **read-only** diagnostics against a
Multi-Hoster-Uploader instance running on a remote Windows server, through the local
**stdio MCP gateway** in `gateway/`.
The gateway is an MCP server to Claude and a WebSocket client to a diagnostic agent inside the
app. It never touches the screen, never injects input, and never writes anything on the server.
---
## 1. Enable diagnostics on the server and copy the code
On the **server** (the machine running the app):
1. Open the app's **Settings**.
2. Enable **"Diagnose-Zugriff"**.
3. Copy the connection **code**. It looks like `mhu1_<base64url...>`.
The code carries a one-time auth **token**. It does **not** carry a host — you supply the host
yourself when you connect. Treat the code as a **secret**: anyone with the code and network reach
to the agent can read diagnostics.
The agent **always binds to `127.0.0.1`** (loopback only) — this is enforced; there is no setting
to expose it on a LAN/Internet interface. You reach it through a tunnel (next step).
**Transport note:** the agent speaks **plaintext `ws://` over loopback**. The token and the
diagnostic data are *not* encrypted on the wire by the agent itself — confidentiality comes
entirely from the **tunnel** (SSH/WireGuard) you put in front of it. The loopback bind means the
plaintext traffic never leaves the host except inside that encrypted tunnel. (A future build may
add `wss`/TLS with cert pinning via an `fp` field in the code; it is not active today.)
---
## 2. Reach the agent over a tunnel (SSH local port-forward or WireGuard)
Because the agent binds to `127.0.0.1` on the server, open a tunnel from your machine to the
server's loopback. The agent's default port is `9110`.
### SSH local port-forward (recommended)
```
ssh -L 9110:127.0.0.1:9110 user@server
```
Leave that session open. Now `127.0.0.1:9110` on **your** machine is forwarded to
`127.0.0.1:9110` on the **server**. You connect Claude to **`127.0.0.1`** (your local end of the
tunnel), not the server's public IP.
### WireGuard (alternative)
Bring up a WireGuard tunnel to the server, then connect to the server's WireGuard address (or, if
you forward loopback over the tunnel, `127.0.0.1`). Use whichever address resolves to the agent's
`127.0.0.1:9110` on the server.
> The agent cannot be bound directly to a LAN/Internet IP in this build (loopback is enforced),
> so the tunnel is the **only** way to reach it remotely — and the only thing encrypting the
> transport. Keep the tunnel (SSH/WireGuard) up for the whole session.
---
## 3. Install the gateway and register it with Claude (one time)
On the machine running Claude Code:
```
cd gateway
npm install
```
Register the gateway as an MCP server (one time):
```
claude mcp add --transport stdio mhu-diag -- node "C:\Users\ploet\Desktop\Claude Projekte\multi-hoster-uploader\gateway\index.js"
```
Adjust the absolute path if your checkout lives elsewhere.
---
## 4. Usage
With the tunnel up, tell Claude:
```
server prod-3 at 127.0.0.1, code mhu1_<...>
```
Claude will:
1. call `connect_server(code:"mhu1_...", host:"127.0.0.1")`,
2. immediately read the app version via `get_system_info`,
3. remember the server under its label in `registry.json`.
Next time you can just say:
```
connect_server(label:"prod-3")
```
with no code — the gateway dials it from the registry. Then ask Claude "what's wrong?" — it will
typically start with **`server_health`**, the one-shot hub that aggregates errors, queue, rotation
and system info in a single call. Other read-only tools: `read_log`, `list_logs`, `list_errors`,
`get_queue_state`, `get_history`, `get_config_redacted`, `get_rotation_state`, `get_app_events`.
---
## 5. Failure → meaning
When a connect or a request fails, the gateway returns a human-readable cause. Quick reference:
| Symptom / signal | What it means / what to do |
| -------------------------------------- | ----------------------------------------------------------------------- |
| `ECONNREFUSED` | app not running / wrong port / inbound firewall closed |
| `ETIMEDOUT` | firewall DROP / NAT not forwarded / tunnel down |
| close code **4001** | auth timeout, retry |
| close code **4002** | stale or rotated code — re-copy the current code from the server |
| close code **4003** | brute-force lockout, wait 60s |
| connected but no `auth-ok` | old app version without the diagnostic agent — update that server |
| wss fingerprint mismatch | reserved for the future TLS mode (not active today) — re-copy the code |
If you tunnel and still get `ECONNREFUSED`, check that the SSH session is up and that the agent is
actually listening on `127.0.0.1:9110` on the server (Diagnose-Zugriff enabled).
---
## 6. What this is — and is not
- It is **READ-ONLY**. It reads logs, errors, queue/history, redacted config, rotation and system
info. **No screen capture. No input injection. No writes or config changes.**
- The **code is a secret** (it carries the auth token). Don't paste it into public channels.
- `gateway/registry.json` stores tokens for remembered servers and is **git-ignored** — never
commit it.