Iw4x Server List File

Title: The IW4x Server List: Architecture, Protocol, and Community Access Abstract IW4x is a community-driven client modification for Call of Duty: Modern Warfare 2 (2009), enabling dedicated servers, custom content, and an improved networking layer. Central to its functionality is the server list —a dynamic, master-server-driven index of available game hosts. This paper examines the IW4x server list’s architecture, the transition from the deprecated XLabs master server to community-maintained alternatives, protocol differences from the original game, and practical methods for viewing, filtering, and modifying the list. 1. Introduction The original Modern Warfare 2 used a peer-to-peer (P2P) matchmaking system via IWNet, which did not expose a traditional server browser. IW4x restores the dedicated server model, requiring a master server to aggregate and distribute active server entries. The server list is the UI and data structure through which players select a server. 2. Technical Architecture 2.1 Components

Master Server ( master.iw4x.xyz historically) : Central registry that receives heartbeats from dedicated servers and serves the list to clients. Dedicated Server : Sends periodic heartbeat packets to the master server with its IP, port, hostname, map, gametype, player count, and mod info. Client : Requests the full server list from the master server via an HTTP-like protocol over raw TCP.

2.2 Protocol IW4x uses a custom binary protocol over TCP port 2086 (or 2087 for SSL in later versions): | Packet Type | Direction | Description | |-------------|--------------------|-------------------------------------------| | 0x01 | Client → Master | Request server list (with optional filters) | | 0x02 | Master → Client | List of servers (compressed) | | 0x03 | Server → Master | Heartbeat registration | | 0x04 | Master → Server | Acknowledgment / rejection | The server list is returned as a gzip-compressed JSON or binary blob containing an array of server objects, each including:

IPv4 address Port (default 28960) Server name (UTF-8) Current map Gametype (e.g., TDM, DOM, S&D) Player count / max players Mod name Password flag Ping time (calculated client-side) iw4x server list

3. Comparison with Original MW2 | Feature | Original MW2 (IWNet) | IW4x Server List | |------------------------|----------------------|---------------------------| | Server discovery | P2P matchmaking only | Central master server | | Filtering | None | Map, gametype, mod, ping, players, password | | Latency display | Bars (obfuscated) | Numeric ping (ms) | | Server favorites | No | Yes (local servers.dat ) | | Direct connect | No (except Steam invite) | Yes via connect IP:port | 4. Current Status (2024–2025) 4.1 XLabs Shutdown In 2023, XLabs (the original IW4x maintainer) ceased development following legal pressure from Activision. Their master server ( master.xlabs.dev ) was taken offline. 4.2 Community Fork – IW4x-Project A community fork at iw4x.gg maintains:

Master server : master.iw4x.gg (port 2086) Client patch : Redirects all master server queries to the new address.

4.3 Fallback & Offline Mode If the master server is unreachable, IW4x can still: Title: The IW4x Server List: Architecture, Protocol, and

Display locally cached server list (last successful fetch) Allow direct IP connections ( /connect 192.168.1.10:28960 ) Show LAN servers (broadcast discovery on 255.255.255.255:28960)

5. Accessing the Server List 5.1 In-Game Browser

Launch IW4x. Click Play → Server List . Use filters (top-right): The server list is the UI and data

Source : Internet / LAN / Favorites / History Game Type : All / TDM / DOM / S&D / etc. Mod : None / specific mod (e.g., Bot Warfare, MW2R) Map : Filter by map name Show full / empty / passworded servers

Double-click a server to join.