Master Server Query Protocol
Send the following UDP query to a master server to get a list of Source host servers.
Format
| Type | Field | Value |
|---|---|---|
| Byte | Message Type | 0x31 - the character "1" |
| Byte | Region Code | See below |
| String Zero | IP:Port | 0.0.0.0:0 |
| String Zero | Filter | See below |
Region Codes
The region of the world that you wish to find servers in.
| Byte | Description |
|---|---|
| 0x00 | US East coast |
| 0x01 | US West coast |
| 0x02 | South America |
| 0x03 | Europe |
| 0x04 | Asia |
| 0x05 | Australia |
| 0x06 | Middle East |
| 0x07 | Africa |
| 0xFF | Rest of the world |
IP:Port
Steam sends "0.0.0.0:0".
Does anyone know what this is supposed to be the address of?
Changing it doesn't appear to affect the results in anyway. (Should be the first ip address we are interested in)
Filter
Allows you to restrict the results to servers running a certain game, map, etc.
Send an empty string (0x00) to recieve a list of all types of servers.
Insert \ in between filter parameters
\type\d
- Servers running dedicated
\secure\1
- Servers using anti-cheat technology (VAC)
\gamedir\[mod]
- Servers running the specified modification (ex. cstrike)
\map\[map]
- Servers running the specified map (ex. cs_italy)
\linux\1
- Servers running on a Linux platform
\empty\1
- Servers that are not empty
\full\1
- Servers that are not full
\proxy\1
- Servers that are spectator proxies
Master Servers
Current master servers are 69.28.151.178:27011, 207.173.177.11:27011, 69.28.151.162:27011.
If you can, get your application to check the file Steam\config\masterservers.vdf to get the latest list of master servers.
Reply Format
The reply always starts with FF FF FF FF 66 0A.
The format is then a series of these server address blocks:
| Type | Data |
|---|---|
| Byte | First octet of IP address |
| Byte | Second octet of IP address |
| Byte | Third octect of IP address |
| Byte | Fourth octet of IP address |
| Short | Port number - usually 27015 (0x69 0x67) |
Some of the servers may be unreachable, so query each server directly to find out. Note also that this list is not exhaustive, so if you're looking for a particular type of server make sure that you specify a filter with the query, rather than filtering client side.