constrain webrtc ice ports

README.md

@@ -80,13 +80,28 @@ To control this computer from your phone/tablet:
 
 ### 1. Configure Firewall
 Ensure your computer allows incoming connections on:
-- **3000** (Frontend + Input Server)
+- **3000/TCP** (Frontend and WebSocket signaling)
+- **4000–4050/UDP** (WebRTC media and input channels)
 
 **Linux (UFW):**
 ```bash
 sudo ufw allow 3000/tcp
+sudo ufw allow 4000:4050/udp
 ```
 
+**NixOS:**
+```nix
+networking.firewall = {
+  allowedTCPPorts = [ 3000 ];
+  allowedUDPPortRanges = [
+    { from = 4000; to = 4050; }
+  ];
+};
+```
+
+Port `5004/UDP` is an internal loopback relay between GStreamer and Rein and
+must not be exposed.
+
 ### 2. Connect Mobile Device
 1.  Ensure your phone and computer are on the **same Wi-Fi network**.
 2.  On your computer, open the app (`http://localhost:3000/settings`).
@@ -233,5 +248,3 @@ flowchart TD
 | **Client settings** | Sensitivity, scroll invert, and theme are stored in `localStorage` on the phone only — no server round-trip. |
 | **Server settings** | Port changes call `POST /api/config`, which writes `server-config.json`. The client redirects to the new port URL. The change is picked up on the next server start. |
 | **Input injection** | Input events arrive at the server via the DataChannel bridge, dispatched through `InputHandler` (throttle + validation), and injected at OS level via a virtual input device. |
-
-

src/server/constants.ts

@@ -22,5 +22,7 @@ export const MAX_KEY_LENGTH = 50
 export const ACCEL_THRESHOLD = 1
 export const ACCEL_FACTOR = 0.8
 export const ACCEL_EXPONENT = 1.2
+export const ICE_PORT_MIN = 4000
+export const ICE_PORT_MAX = 4050
 export const RTP_HOST = "127.0.0.1"
 export const RTP_PORT = 5004

src/server/webRTC.ts

@@ -13,7 +13,7 @@ import type { InputMessage, InputConfig } from "./types"
 import fs from "node:fs"
 import { fileURLToPath } from "node:url"
 import { isKnownToken } from "./tokenStore"
-import { RTP_HOST, RTP_PORT } from "./constants"
+import { ICE_PORT_MAX, ICE_PORT_MIN, RTP_HOST, RTP_PORT } from "./constants"
 
 interface ClientSession {
 	ws: WebSocket
@@ -213,6 +213,7 @@ export class WebRTCManager {
 
 			const pc = new RTCPeerConnection({
 				iceServers: [{ urls: "stun:stun.l.google.com:19302" }],
+				icePortRange: [ICE_PORT_MIN, ICE_PORT_MAX],
 				codecs: {
 					video: [
 						new RTCRtpCodecParameters({