Call of Duty: Modern Warfare 3 Server Guide
📋 Quick Info
Server Specifications
- Game: Call of Duty: Modern Warfare 3 (2011)
- Platform: Windows
- Default Port:
Varies (configurable)
- Max Players: 18 (engine limitation)
- Control Protocol: RCON
- Executable: iw5mp_server.exe
- Special: Multi-port configuration required
🔌 Ports & Firewall Configuration
Modern Warfare 3 servers require multiple port configurations for proper operation:
| Port |
Protocol |
Purpose |
Required |
| 27016 (configurable) |
UDP |
Game port |
Yes |
| Game port - 1 |
UDP |
Query port (net_queryPort) |
Yes |
| -18249 |
UDP |
Auth port (net_authPort) |
Yes |
| Same as game port |
TCP |
RCON remote control |
Optional |
Firewall Examples
UFW (Ubuntu/Debian):
sudo ufw allow 27016/udp comment 'MW3 Game Port'
sudo ufw allow 27015/udp comment 'MW3 Query Port'
sudo ufw allow 27016/tcp comment 'MW3 RCON'
Windows Firewall:
netsh advfirewall firewall add rule name="MW3 Game" dir=in action=allow protocol=UDP localport=27016
netsh advfirewall firewall add rule name="MW3 Query" dir=in action=allow protocol=UDP localport=27015
netsh advfirewall firewall add rule name="MW3 RCON" dir=in action=allow protocol=TCP localport=27016
⚙️ Installation & Setup
System Requirements
- OS: Windows 7/8/10/11 or Windows Server 2016+
- CPU: 2+ cores @ 2.5GHz recommended
- RAM: 2GB minimum, 4GB recommended
- Disk: 20GB for game files
- Network: Low latency connection, 10Mbps+ bandwidth
- Requirements: Legitimate MW3 game files
Installation Steps
- Install Modern Warfare 3: You must have legitimate MW3 game files
- Locate Dedicated Server Files: Server files included with MW3 installation
- Create Server Directory: Separate directory recommended for dedicated server
- Create Server Config: Create
server.cfg in players2 folder
- Configure Firewall: Allow required ports through Windows Firewall
📝 Configuration
Basic server.cfg Example
// Server Name
set sv_hostname "My MW3 Server"
// Network Settings (CRITICAL - Multi-port configuration)
set net_port 27016
set net_queryPort -1 // Auto-set to net_port - 1 (27015)
set net_masterServerPort -1 // Disable master server
set net_authPort -18249 // Auth port offset
// Server Type
set dedicated 2
// Player Limits (MAX 18 for MW3)
set sv_maxclients 18
// RCON Password
set rcon_password "your_secure_password_here"
// Game Settings
set g_gametype "war" // dm, war, sab, koth, sd, dom, dd, ctf
set sv_maxPing 350
// Map Rotation
set sv_mapRotation "gametype war map mp_dome gametype war map mp_hardhat gametype war map mp_seatown"
// Password Protection (leave empty for public)
set g_password ""
// Friendly Fire
set scr_team_fftype 0 // 0=off, 1=on, 2=reflect
// Kill Cam
set scr_game_allowkillcam 1
// Hardcore Mode
set scr_hardcore 0
// Game Log
set g_log "games_mp.log"
set logfile 2
// Voice Chat
set sv_voice 0
// Anti-Lag
set sv_fps 20
// Auto-Balance
set scr_teambalance 1
🚀 Startup Parameters
| Parameter |
Description |
Example |
| +set dedicated |
Server mode (2=Internet) |
+set dedicated 2 |
| +set net_port |
Main game port |
+set net_port 27016 |
| +set net_queryPort |
Query port (-1 for auto: port-1) |
+set net_queryPort -1 |
| +set net_authPort |
Auth port (-18249 standard) |
+set net_authPort -18249 |
| +set net_masterServerPort |
Master server port (-1 to disable) |
+set net_masterServerPort -1 |
| +set sv_maxclients |
Maximum player slots (MAX 18) |
+set sv_maxclients 18 |
| +set rcon_password |
RCON password for remote admin |
+set rcon_password "secret123" |
| +exec |
Execute config file on startup |
+exec server.cfg |
| +map_rotate |
Start map rotation from config |
+map_rotate |
| +map |
Start with specific map |
+map mp_dome |
Example Startup Command
iw5mp_server.exe +set dedicated 2 +set net_port 27016 +set net_queryPort -1 +set net_authPort -18249 +set net_masterServerPort -1 +set sv_maxclients 18 +exec server.cfg +map_rotate
Example Batch File (start_server.bat)
@echo off
title MW3 Dedicated Server
iw5mp_server.exe +set dedicated 2 +set net_port 27016 +set net_queryPort -1 +set net_authPort -18249 +set net_masterServerPort -1 +set sv_maxclients 18 +exec server.cfg +map_rotate
pause
🔧 Troubleshooting
Server Not Appearing in Browser
Issue: Players cannot see the server in MW3 browser.
Solutions:
- Verify all required ports are open (game, query, auth)
- Ensure
+set dedicated 2 is set
- Check
net_queryPort is set to -1 (auto)
- Verify
net_authPort -18249 is configured
- Try direct connect using IP:PORT
Port Configuration Issues
Issue: Server fails to start or clients cannot connect.
Solutions:
- MW3 requires specific port configuration:
- Game port: Your chosen port (e.g., 27016)
- Query port: Set to -1 (automatically becomes game port - 1)
- Auth port: Must be set to -18249
- Master server port: Set to -1 (disabled)
- Verify all three ports are open in firewall
Server Crashes on Startup
Issue: Dedicated server crashes immediately after launch.
Solutions:
- Check
games_mp.log for error messages
- Verify all required MW3 game files are present
- Ensure
server.cfg syntax is correct
- Verify
sv_maxclients does not exceed 18
- Check that port configuration is correct
Connection Problems
Issue: Players cannot connect or timeout.
Solutions:
- Verify firewall rules allow traffic on all required ports
- Check
sv_maxPing setting
- Ensure server is not full (max 18 players)
- Disable password if testing:
set g_password ""
- Verify clients are using same MW3 version
High Lag/Ping Issues
Issue: Players experience significant lag.
Solutions:
- Increase
sv_fps setting (recommended: 20)
- Reduce
sv_maxclients if server is overloaded
- Check server CPU and RAM usage
- Verify network bandwidth is sufficient
- Lower
sv_maxPing to restrict high-ping players
Player Limit Issues
Issue: Cannot set more than 18 players.
Solutions:
- MW3 has a hard limit of 18 players - this is by design
- Do not attempt to exceed this limit as it will cause issues
- This is an engine limitation, not a configuration issue
RCON Not Working
Issue: Cannot connect via RCON.
Solutions:
- Verify
rcon_password is set in server.cfg
- Ensure TCP port is open (same as game UDP port)
- Use MW3-compatible RCON tools
- Test RCON from in-game console first
🎮 Game Types
Modern Warfare 3 supports the following game modes:
- dm - Deathmatch (Free-for-all)
- war - Team Deathmatch
- sab - Sabotage
- koth - Headquarters (King of the Hill)
- sd - Search & Destroy
- dom - Domination
- dd - Demolition
- ctf - Capture the Flag
🗺️ Default Maps
Modern Warfare 3 includes the following multiplayer maps:
Base Game Maps
- mp_dome - Dome
- mp_hardhat - Hardhat
- mp_paris - Resistance
- mp_seatown - Seatown
- mp_bravo - Mission
- mp_underground - Underground
- mp_village - Village
- mp_alpha - Lockdown
- mp_bootleg - Bootleg
- mp_carbon - Carbon
- mp_exchange - Downturn
- mp_hillside_ss - Fallen
- mp_interchange - Interchange
- mp_lambeth - Lambeth
- mp_mogadishu - Bakaara
- mp_plaza2 - Arkaden
DLC Maps
- Collection 1: Liberation, Piazza, Overwatch, Black Box
- Collection 2: Sanctuary, Foundation, Oasis, Terminal (MW2 remake)
- Collection 3: Boardwalk, Parish, Off Shore, Gulch
- Collection 4: Intersection, Vortex, U-Turn, Lookout
Popular server modifications compatible with MW3:
- B3 (Big Brother Bot) - Python-based admin bot with RCON wrapper, player warnings, ban management, statistics tracking, and automated moderation for Call of Duty servers
- Custom GSC Scripts - Server-side gameplay modifications
📚 Resources
- Community Forums: MW3 modding and server communities
- Documentation: Limited official documentation available
- RCON Tools: B3, various web-based RCON panels
Important Notes
- Maximum 18 players - this is a hard engine limit and cannot be exceeded
- MW3 requires multi-port configuration for proper operation:
- Game port: Your chosen port
- Query port: -1 (auto: game port - 1)
- Auth port: -18249 (required)
- Master server port: -1 (disabled)
- You must own legitimate Modern Warfare 3 game files
- MW3 is Windows-only for dedicated servers
- The
players2 folder contains server configuration and data
- Always secure your RCON password and restrict access
- Regular backups recommended for server configurations
- Ensure all three required ports (game, query, auth) are open in firewall