Port 604

tunnel · TCP/UDP

RangeSystem/well-known port (0–1023)
ProtocolTCP/UDP
Servicetunnel
ReferenceRFC 3620

Frequently asked questions

What is port 604 used for?

Port 604 is registered with the IANA for tunnel (TCP/UDP). Description: TUNNEL.

Is port 604 a well-known port?

Yes. Port 604 is in the range 0–1023 (system or well-known ports). On Linux and macOS only privileged processes may bind to these ports.

How do I check whether port 604 is open?

Locally on Linux with ss -tulpn | grep ':604\b', on Windows with netstat -ano | findstr :604. To test a remote host use Test-NetConnection <host> -Port 604 in PowerShell or nc -zv <host> 604 on Linux/macOS.

How do I open port 604 in the firewall?

Ubuntu/Debian (ufw): sudo ufw allow 604/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=604/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 604" -Direction Inbound -Protocol TCP -LocalPort 604 -Action Allow.

IANA registry entries

ProtocolServiceDescription (IANA)
TCPtunnelTUNNEL
UDPtunnelTUNNEL

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