CS 1.6 Network Layer - UDP Protocol

Master
Server Intel

The Master Server is the first point of contact when your CS 1.6 client searches for game servers. Monitor status, query server lists, and configure your MasterServers.vdf from this panel.
Protocol: HL1 MSQP UDP
Default Port: 27010
Config: MasterServers.vdf
Auto-refresh: 30s
MS
Panel Active
Masters Monitored: 1
Total Servers: -
Total Players: -
Last Query: -
Active Master: -
Master Servers

Network Nodes

LongHorn CStrike
LongHorn CS MasterServer
Checking... - ms
Servers -
Players -
Region Global
Not queried
Server List

Active Game Servers

Select a master server to load
o IP : Port Server Name Map Players Ping LOCK
Select a master server above and click Query Now to load server list
Configuration

MasterServers.vdf Config

MasterServers.vdf - Copy-Ready Config
// Drop this file into your Steam config directory to point your CS 1.6 client at these master servers
// MasterServers.vdf - Counter-Strike 1.6 // Generated by CS16 Master Server Panel // Place in: Steam\config\MasterServers.vdf // ----------------------------------------- "MasterServers" { "hl1" { "0" { "addr" "hl1master.steampowered.com" } } } // LongHorn CStrike MasterServer // Powered By: LongHorn - http://www.cslonghorn.com
Windows path: C:\Program Files (x86)\Steam\config\MasterServers.vdf  |  Linux: ~/.steam/steam/config/MasterServers.vdf
Protocol

How Master Servers Work

01
Client Contacts Master
When you open the Server Browser in CS 1.6, the game reads MasterServers.vdf and sends a UDP request to the master server on port 27010. The packet includes a filter (\gamedir\cstrike) and a starting IP of 0.0.0.0:0.
02
Master Returns IP List
The master replies with a batch of up to ~230 IP:port pairs per packet. The client re-queries with the last IP received until a terminator (0.0.0.0:0) signals the end. The full list can contain thousands of servers.
03
Client Queries Each Server
For each IP:port returned, the CS 1.6 client sends an A2S_INFO UDP query (port 27015) to get the server's name, map, player count, and VAC status. Only reachable servers appear in the browser list.
04
HLDS Server Registration
A game server registers itself on the master by sending heartbeat packets via the setmaster console command or automatically via HLDS. If the master is unreachable, the server won't appear in any public list.
05
Why Use a Stable Master
A stable master endpoint improves discoverability and response consistency for your players, especially during peak load or regional routing issues.
06
Single Endpoint Mode
This panel is configured for a single editable master endpoint so your server discovery and troubleshooting stay simple and predictable.