Port 27015: Steam / Source
TCP/UDP 27015 is the port for Steam game servers (Source engine: CS2, Garry's Mod, Rust). Game traffic yes; protect RCON with a strong password.
| Service | Steam game servers (Source engine: CS2, Garry's Mod, Rust) |
|---|---|
| Protocol | TCP/UDP |
| Exposure risk | Low: normally safe to expose |
| Range | Registered (1024–49151) |
What port 27015 does
Source-engine dedicated servers listen for players on UDP 27015 and RCON admin on TCP 27015.
Should port 27015 be open?
Game traffic yes; protect RCON with a strong password.
Find what's listening on port 27015
- Linux:
sudo ss -tulpn | grep :27015 - macOS:
sudo lsof -nP -i :27015 - Windows:
netstat -ano | findstr :27015, then look up the PID in Task Manager.
Open or block it in a firewall
- ufw:
sudo ufw allow 27015/tcp(ordeny) - firewalld:
sudo firewall-cmd --add-port=27015/tcp --permanent && sudo firewall-cmd --reload - Windows:
New-NetFirewallRule -DisplayName "Port 27015" -Direction Inbound -Protocol TCP -LocalPort 27015 -Action Allow
Port assignment per the IANA Service Name and Transport Protocol Port Number Registry. Test several ports at once with the port scanner, or any port with the open port checker.
Questions about port 27015
What is port 27015 used for?
Steam game servers (Source engine: CS2, Garry's Mod, Rust). Source-engine dedicated servers listen for players on UDP 27015 and RCON admin on TCP 27015.
Is port 27015 TCP or UDP?
Both. Steam / Source uses TCP and UDP on port 27015.
Is it safe to open port 27015?
Low: normally safe to expose. Game traffic yes; protect RCON with a strong password.
How do I check if port 27015 is open?
Use the checker on this page: it connects to your host on TCP 27015 from the internet. Locally, run
nc -vz host 27015 (macOS/Linux) or Test-NetConnection host -Port 27015 (PowerShell). To see what is listening on your own machine, run ss -tulpn | grep :27015 (Linux) or netstat -ano | findstr :27015 (Windows).