Core Keeper Server Default Port & How to Change It
The default port for a Core Keeper dedicated server is 27015 (UDP). You can change it by editing the server.cfg file (or the command line when starting the server) and adjusting the Port setting.
Background: How Core Keeper Networking Works
Core Keeper uses a peer-to-peer model for standard multiplayer sessions, where the host’s game acts as the server. However, for a dedicated server (which runs 24/7 without requiring a player to be in the world), the game uses the Steam networking layer. This means the server communicates through Steam’s relay system by default, which often works without any port forwarding. But if you want direct connections (for lower latency or to avoid Steam relay issues), you need to open a specific UDP port on your router and firewall.
Default Port and Protocol
The default port is 27015, and it uses the UDP protocol. This is a common default for many Source-engine and Steam-based games, but Core Keeper is a Unity game that uses Steam’s networking APIs. When you run a dedicated server, it listens on this port for incoming connections. If you are hosting a non-dedicated session (playing and hosting at the same time), the game may use a different dynamic port, but the dedicated server always defaults to 27015.
How to Change the Default Port
There are two main ways to change the port: editing the configuration file or passing a command-line argument. Both methods are straightforward.
Method 1: Editing server.cfg
- Navigate to your Core Keeper dedicated server folder. If you installed it via Steam, it is typically in
steamapps/common/Core Keeper Dedicated Server/. - Open the file named
server.cfgwith a text editor (like Notepad). - Find the line that says
Port=27015. - Change the number to your desired port (e.g.,
Port=27016). - Save the file and restart the server.
Method 2: Command-Line Argument
If you start the server via a batch file or command prompt, you can add the argument -port=27016 (replace with your desired port). For example:
CoreKeeperServer.exe -port=27016This overrides the setting in the config file for that session.
Choosing a New Port
When selecting a new port, consider the following:
- Use a number between 1024 and 65535 (ports below 1024 are reserved for system services).
- Avoid ports already used by other services on your machine (e.g., 80 for HTTP, 443 for HTTPS, 3306 for MySQL).
- Pick a port that is not commonly used by other games to reduce the chance of conflicts.
- If you have multiple Core Keeper servers, each must use a unique port.
Port Forwarding and Firewall
For players to connect directly to your server over the internet, you must forward the chosen UDP port on your router to the computer running the server. You also need to allow inbound UDP traffic on that port in your firewall. The exact steps vary by router brand, but generally:
- Log into your router’s admin panel (usually at 192.168.1.1 or 192.168.0.1).
- Find the “Port Forwarding” or “Virtual Server” section.
- Create a new rule: set the service type to UDP, external port to your chosen port, internal port to the same port, and the internal IP address to your server’s local IP.
- Save the rule and restart the router if needed.
If you are using a hosting service, you may not need to do this yourself—the provider usually handles port forwarding.
Common Problems and Troubleshooting
Here are typical issues and how to resolve them:
- Server not visible in the list: If you changed the port, make sure you also update any server browser filters or direct connect IPs (e.g.,
ip:port). - Connection timed out: This usually means the port is not forwarded correctly, or the firewall is blocking it. Double-check the UDP rule and that the server is listening on the correct port (check server logs).
- Port already in use: Another application is using the same port. Choose a different one or close the conflicting program.
- Steam relay still used: Even with port forwarding, the game may still prefer Steam relay unless you set
SteamNetworking=0in the config (if available). This is not always necessary, but can be done for direct connections.
Security and Safety Considerations
Opening a port to the internet exposes your server to potential attacks. Always keep your server software up to date. Consider using a firewall to restrict access to trusted IPs if you are playing with a small group. Do not share your server’s IP and port publicly unless you are okay with strangers joining. Also, be aware that port forwarding can be a security risk if you do not trust the game’s code—use a dedicated machine or a virtual private server (VPS) if possible.
Frequently Asked Questions
Is the default port TCP or UDP?
It is UDP. Core Keeper’s dedicated server uses UDP for game traffic. Some server tools may also use TCP for console commands, but the game data is UDP.
Do I need to change the port if I only play with friends via Steam?
No. If you are using Steam’s invite system, the game will use Steam’s relay servers, and you do not need to forward any ports. Port forwarding is only needed for direct connections, which is optional.
Can I run multiple Core Keeper servers on the same machine?
Yes, but each server must use a different port. You can also use different world save folders to keep them separate.
How do I find out which port my server is using?
Check the server console output when it starts—it usually prints the port. You can also check the server.cfg file or the command line you used to start it.
What if I forget to change the port in both the config and the command line?
The command-line argument takes precedence over the config file. If you set a port in both, the command-line one will be used. To avoid confusion, only set it in one place.
Will changing the port affect my saved world?
No. The port is a network setting; it does not affect your world data. Your save files are stored separately and will load normally.
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