Killing Floor 2 Port Forwarding Guide
Open the correct firewall ports for a KF2 dedicated server: UDP 7777 (game traffic), UDP 27015 (Steam query), TCP/UDP 20560 (Steam), and TCP 8080 (WebAdmin).
Killing Floor 2 Port Forwarding
For players to connect and for your server to appear in the Steam server browser, four ports must be open on your host firewall.
Required Ports
| Port | Protocol | Purpose |
|---|---|---|
| 7777 | UDP | Game traffic — player connections |
| 27015 | UDP | Steam query — server browser & status |
| 20560 | UDP | Steam client communications |
| 8080 | TCP | WebAdmin panel (browser-based admin UI) |
If you changed the default game port (e.g. to
7778), the query port automatically follows (27016). The WebAdmin port is set separately inKFWeb.ini.
Opening Ports with UFW (Ubuntu/Debian)
sudo ufw allow 7777/udp
sudo ufw allow 27015/udp
sudo ufw allow 20560/udp
sudo ufw allow 8080/tcp
sudo ufw reload
Verify with sudo ufw status — all four should show ALLOW.
Opening Ports with firewalld (CentOS/RHEL/Fedora)
sudo firewall-cmd --permanent --add-port=7777/udp
sudo firewall-cmd --permanent --add-port=27015/udp
sudo firewall-cmd --permanent --add-port=20560/udp
sudo firewall-cmd --permanent --add-port=8080/tcp
sudo firewall-cmd --reload
Opening Ports with iptables
iptables -A INPUT -p udp --dport 7777 -j ACCEPT
iptables -A INPUT -p udp --dport 27015 -j ACCEPT
iptables -A INPUT -p udp --dport 20560 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j ACCEPT
Persist these rules using iptables-save > /etc/iptables/rules.v4 or your distro's equivalent.
Running Multiple Servers on One Machine
Each server instance needs its own port set. Increment the game port by 1 for each additional instance:
| Instance | Game Port | Query Port | WebAdmin Port |
|---|---|---|---|
| Server 1 | 7777 | 27015 | 8080 |
| Server 2 | 7778 | 27016 | 8081 |
| Server 3 | 7779 | 27017 | 8082 |
Launch each instance with -Port=7778 (etc.) and update KFWeb.ini with the correct WebAdmin port per instance.
Verifying Ports Are Open
After opening ports and starting the server, test from an external machine:
# Test UDP query port
nmap -sU -p 27015 YOUR_SERVER_IP
# Test WebAdmin TCP port
curl -I http://YOUR_SERVER_IP:8080
If the Steam server browser still doesn't show your server after 5–10 minutes, double-check that your cloud/VPS provider's security group or external firewall also has these ports open — many providers have a separate layer from the OS firewall.