Multi-Hoster-Upload/docs/remote-diagnostics-setup.md
Administrator 0c6c502aab feat(diagnostics): network bind + fail-closed IP allowlist + host-in-code (Tailscale, like rd-diagnostics-mcp)
Matches the Real-Debrid-Downloader's rd-diagnostics-mcp model so the read-only
diagnostics agent is reachable over Tailscale (or any private tunnel) the same way
the downloader is, instead of requiring an SSH local-forward.

- lib/ip-allowlist.js (NEW): fail-closed IP allowlist — normalizeIp strips
  ::ffff:, loopback is always allowed, an empty allowlist accepts loopback ONLY
  (fail-closed), exact IP + CIDR (incl. the Tailscale CGNAT range 100.64.0.0/10) +
  wildcard rules. The real socket peer IP is the authority (never a forwarded header).
- remote-server.js: rejects non-allowlisted peers at connection (close 4005). Opt-in
  via config.allowlist (the existing remote-control server, which passes none, is
  unaffected). Loopback always passes, so local + SSH-forward use keeps working.
- Two bind modes (config diagnostics.bindMode): "local" -> 127.0.0.1 (default),
  "network" -> 0.0.0.0 but ONLY when a non-empty allowlist is set (else it stays
  loopback, fail-closed). The allowlist + token gate access; the tunnel
  (Tailscale/WireGuard) is the confidentiality layer (transport is still plaintext ws://).
- The connection code now carries the host: mhu1_<base64url{v,h,p,t,n,fp?,s?}>. The
  gateway decode is tolerant of the legacy {port,token,label} keys; connect_server
  takes the host from the code (host arg is an optional override). Proven end-to-end:
  the integration harness now connects with NO host arg and resolves it from the code.
- Renderer: Sichtbarkeit selector (local/network), public-host input with
  suggested-host chips (os.networkInterfaces — the Tailscale IP shows up there),
  allowlist textarea (network mode), and network-requires-allowlist validation.
- main.js: bindMode->host, getSuggestedRemoteHosts, host-in-code, allowlist plumbed
  into startDiagnosticAgent + the diagnostics IPC (get/save/status).
- docs: rewritten for Tailscale (set the allowlist to your tailnet, put the Tailscale
  IP/MagicDNS in the code address — no SSH forward needed).

This supersedes the v3.3.85 hard loopback-lock with the downloader's allowlist model.
Tests: lib/ip-allowlist (8) + remote-server allowlist wiring/loopback (2) + gateway
decode (host short-key + legacy tolerance). 393 app tests + 9 gateway tests + e2e +
host-in-code integration + adversarial all green; lint 0 errors.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-19 19:32:29 +02:00

149 lines
6.5 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 the **host**, **port** and a one-time auth **token** (`mhu1_<base64url{v,h,p,t,n}>`).
The bridge dials the host from the code, so you usually just hand over the code. Treat the code as a
**secret**: anyone with the code and network reach to the agent can read diagnostics.
**Two visibility modes** (Settings → Diagnose-Zugriff → Sichtbarkeit):
- **Nur lokal** (default): the agent binds to `127.0.0.1`. Reach it through a tunnel (next step).
- **Im Netzwerk**: the agent binds to `0.0.0.0` but is gated by a **fail-closed IP allowlist** — only
source IPs/CIDRs you list may connect (loopback is always allowed), *in addition to* the token. An
empty allowlist means loopback only. This is the mode to use with **Tailscale**: set the allowlist
to your tailnet (e.g. `100.64.0.0/10`) and put the server's Tailscale IP / MagicDNS name into the
code address — then the bridge connects straight over the tailnet, no SSH forward needed.
**Transport note:** the agent speaks **plaintext `ws://`**. The token and the diagnostic data are
*not* encrypted on the wire by the agent itself — confidentiality comes from the **tunnel**
(Tailscale/WireGuard/SSH) you reach it through. In network mode the IP allowlist + token are the
access gate; **only bind to the network behind a private tunnel you trust** (a tailnet, a VPN, or a
trusted LAN). (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
The agent's default port is `9110`. Pick the path that matches your setup.
### Tailscale (recommended for many servers)
Put every server and your gateway machine on the same tailnet. On each server, set **Sichtbarkeit =
Im Netzwerk**, allowlist your tailnet (`100.64.0.0/10`, or the specific Tailscale IPs you'll connect
from), and set the **code address** to that server's Tailscale IP or MagicDNS name. The bridge then
connects straight to `<tailscale-name>:9110` — WireGuard (Tailscale) encrypts the transport, and the
allowlist + token gate access. No SSH forward, no per-session tunnel command.
### SSH local port-forward (keep the agent loopback-only)
With **Sichtbarkeit = Nur lokal**:
```
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 the server's
loopback. The code address is `127.0.0.1` (your local end of the tunnel).
### WireGuard (manual, alternative)
Bring up a WireGuard tunnel and either bind the agent to the network with the peer's WG IP in the
allowlist, or forward loopback over the tunnel and connect to `127.0.0.1`.
> In **Nur lokal** mode the agent is unreachable except through a tunnel to loopback. In **Im
> Netzwerk** mode the fail-closed IP allowlist (plus the token) is the access gate — only bind to
> the network behind a tunnel/VPN you trust (a tailnet, WireGuard, or a trusted LAN). The transport
> is plaintext; the tunnel is what encrypts it.
---
## 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.