Port 900
omginitialrefs · TCP/UDP
| Range | System/well-known port (0–1023) |
|---|---|
| Protocol | TCP/UDP |
| Service | omginitialrefs |
Frequently asked questions
What is port 900 used for?
Port 900 is registered with the IANA for omginitialrefs (TCP/UDP). Description: OMG Initial Refs.
Is port 900 a well-known port?
Yes. Port 900 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 900 is open?
Locally on Linux with ss -tulpn | grep ':900\b', on Windows with netstat -ano | findstr :900. To test a remote host use Test-NetConnection <host> -Port 900 in PowerShell or nc -zv <host> 900 on Linux/macOS.
How do I open port 900 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 900/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=900/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 900" -Direction Inbound -Protocol TCP -LocalPort 900 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | omginitialrefs | OMG Initial Refs |
| UDP | omginitialrefs | OMG Initial Refs |