Open Fortress Server Port Forwarding
Open UDP 27015 and UDP 27005 on your firewall and router to make your Open Fortress dedicated server reachable from the internet.
Port Forwarding for Open Fortress
Open Fortress uses the Source Engine networking stack. Two UDP ports must be open for a public server to function correctly.
Required Ports
| Port | Protocol | Purpose |
|---|---|---|
| 27015 | UDP | Primary game port — gameplay, server browser queries, RCON |
| 27005 | UDP | Client connection port — used by the Source client during handshake |
Both ports must be open inbound. If either is blocked, players will either fail to connect entirely or time out during connection.
Changing the Port
The primary port defaults to 27015. Override it with the -port argument at launch:
./srcds_run -console -game open_fortress -port 27016 ...
The client port (27005) adjusts automatically relative to the primary port. If you change -port, you only need to forward the new primary port and 27005.
Linux — UFW
sudo ufw allow 27015/udp
sudo ufw allow 27005/udp
sudo ufw reload
Verify the rules are active:
sudo ufw status
You should see both ports listed as ALLOW.
Linux — iptables (without UFW)
sudo iptables -A INPUT -p udp --dport 27015 -j ACCEPT
sudo iptables -A INPUT -p udp --dport 27005 -j ACCEPT
sudo iptables-save > /etc/iptables/rules.v4
Windows Firewall
Open PowerShell as Administrator:
New-NetFirewallRule -DisplayName "Open Fortress Game Port" `
-Direction Inbound -Protocol UDP -LocalPort 27015 -Action Allow
New-NetFirewallRule -DisplayName "Open Fortress Client Port" `
-Direction Inbound -Protocol UDP -LocalPort 27005 -Action Allow
Or use the Windows Defender Firewall GUI: Inbound Rules → New Rule → Port → UDP → 27015, then repeat for 27005.
Router Port Forwarding
If your server is behind a home router or NAT, also forward the ports on the router:
- Log into your router admin panel (typically
192.168.1.1or192.168.0.1) - Find Port Forwarding or Virtual Server settings
- Add a UDP rule: external port 27015 → internal IP of your server → internal port 27015
- Repeat for UDP 27005
- Save and apply
Cloud / VPS Providers
Most VPS and cloud providers have an additional security group or firewall layer outside the OS. Check your provider's dashboard:
- Hetzner — Firewall rules in the Cloud Console
- OVH/Kimsufi — Network → Firewall Manager
- AWS — EC2 Security Groups → Inbound rules
Add UDP 27015 and UDP 27005 there in addition to your OS-level firewall.
Testing Connectivity
After opening the ports, test from outside your network. Search for your server's public IP in the in-game server browser, or use a Source query tool to ping <your-ip>:27015.
If the server appears in the browser but players time out on join, UDP 27005 is likely blocked.