How to Open Ports for Your Barotrauma Server
Open UDP 27015 for your Barotrauma server. Covers firewall rules, running multiple servers on different ports, and testing connectivity.
The Port You Need
Barotrauma uses a single port for both game traffic and Steam queries:
| Protocol | Port | Purpose |
|---|---|---|
| UDP | 27015 | Game traffic + Steam server query |
Open UDP 27015 in your firewall or server control panel. TCP is not needed.
Opening the Port
In your hosting control panel or firewall, create an inbound rule:
- Protocol: UDP
- Port: 27015
- Action: Allow
If you're on a home network, you'll also need a port forward rule on your router pointing UDP 27015 to the machine running the server. Your router's admin panel (usually 192.168.1.1 or 192.168.0.1) is where you set that up.
On a VPS or dedicated machine, the control panel firewall is usually all you need — there's no router in between.
Running Multiple Servers
Each server instance needs its own unique port. Change the port in serversettings.xml:
<serversettings
Port="27016"
...
/>
Then open that port in your firewall as well. Repeat for each additional instance (27017, 27018, etc.).
Testing Connectivity
Once the server is running:
- Go to canyouseeme.org
- Enter port 27015
- Select UDP
- Hit Check — if it succeeds, players can reach your server directly
If the check fails but your server is running, double-check the firewall rule and make sure the server process is actually listening.
Steam Networking Relay
Barotrauma supports Steam's networking relay. In some cases players can connect via Steam even if your port isn't open directly to the internet — the relay tunnels traffic through Steam's infrastructure. This works but:
- Latency is higher than a direct connection
- It's not guaranteed to work for all players
- You should still open the port for the best experience
Server Not Showing in the Browser
After opening the port, the Steam server list can take 2–5 minutes to propagate. If your server still doesn't appear:
- Confirm
isPublic="true"inserversettings.xml - Restart the server after any config change
- Try Direct Join in the server browser using your IP and port to test before relying on the listing