White Paper: IW4x Server List Infrastructure & Update Protocols

Subject: Technical Overview of the IW4x Server Browser, Master Server Interaction, and Synchronization Standards. Date: October 26, 2023 Audience: Server Administrators, Client Developers, End-Users.

1. Introduction

IW4x is a reverse-engineered modification for Call of Duty: Modern Warfare 2 (IW4 engine). Unlike the Steam version, which relies on Valve’s master server infrastructure, IW4x utilizes a custom backend to facilitate peer-to-peer and dedicated server discovery. An "updated" server list implies a client successfully communicating with the master server, receiving a peer list, and querying those peers for latency and player counts.

Method 3: Direct Connect (Bypass list issues)

If the server list remains empty, you can still join servers manually:

Find active servers on iw4x.gsc.re or the XLabs Discord.
Copy an IP:Port (e.g., 192.168.1.100:28960).
In IW4x, open console (~ key) and type:
```
connect 192.168.1.100:28960
```

The "No Servers Found" Bug

The most common complaint currently is the empty server list. Users report launching IW4x, seeing the "updated" status, but staring at a blank browser.

Why is this happening?

Project Discontinuation: The original developers of IW4x (XLabs) have largely moved on to other projects (like H2M for MW2 Remastered). The master server is running on community life support.
DNS Issues: Many users are finding that the client cannot ping iw4x.another.dev or master.iw4x.xyz.

2.1 The Handshake Protocol

When a user clicks "Refresh" or starts the client, the following handshake occurs:

Request: The client sends a UDP packet to the configured Master Server IP.
Response: The Master Server responds with a list of IP addresses and ports currently "heartbeat-ing" (signaling they are online).
Direct Query: The client sends "getinfo" requests directly to every IP provided in the Master Server list.
Population: The client parses the responses (ping, hostname, map, gametype) and populates the UI table.