Port 20003

commtact-https · TCP/UDP

RangeRegistered port (1024–49151)
ProtocolTCP/UDP
Servicecommtact-https
Registered2004-12

Frequently asked questions

What is port 20003 used for?

Port 20003 is registered with the IANA for commtact-https (TCP/UDP). Description: Commtact HTTPS.

Is port 20003 a well-known port?

No. Port 20003 is in the range 1024–49151 (registered or user ports). Ordinary programs may open it without root privileges.

How do I check whether port 20003 is open?

Locally on Linux with ss -tulpn | grep ':20003\b', on Windows with netstat -ano | findstr :20003. To test a remote host use Test-NetConnection <host> -Port 20003 in PowerShell or nc -zv <host> 20003 on Linux/macOS.

How do I open port 20003 in the firewall?

Ubuntu/Debian (ufw): sudo ufw allow 20003/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=20003/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 20003" -Direction Inbound -Protocol TCP -LocalPort 20003 -Action Allow.

IANA registry entries

ProtocolServiceDescription (IANA)
TCPcommtact-httpsCommtact HTTPS
UDPcommtact-httpsCommtact HTTPS

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