Registry assignments, software defaults and local listeners are different things. A port number alone does not identify or secure a service.
Software Using This Port (2 software)
Community software entries: links are references, not individual verification.
discard
ProtocolService
Network Testing
NetworkTestingTool
Usage Suggestions
- Before using port 9, please confirm it is not occupied by other services
- If you encounter port conflicts, consider using other ports or stopping the occupying service
Frequently asked questions
What is port 9 used for?
Port 9 sits in the System category. This page lists the registered purpose and the software commonly associated with it; to see what is actually listening on a specific machine, check the process with ss/netstat.
Is port 9 TCP or UDP?
The registered protocol on this page is UDP. The same number behaves independently on each protocol: TCP may be listening while UDP is idle, so check them separately.
How do I check if port 9 is in use?
On Linux: sudo ss -tlnp 'sport = :9' for an exact port match. On macOS: sudo lsof -nP -iTCP:9 -sTCP:LISTEN. On Windows PowerShell: Get-NetTCPConnection -LocalPort 9 -State Listen. A listener counts as confirmed only when you can see the bind address and process name; without root/admin you will not see other users' processes.
Is port 9 secure? Should I open it in my firewall?
A port number has no inherent security — it depends on whether the listening service is correctly configured and whether it needs exposure at all. Keep loopback/internal-only services firewalled; where public access is required, pair it with source restrictions, VPN or authentication.
Quick Info
- Port
- 9
- Protocol
- UDP
- Categories
- System
- Usage Status
- 2 software in use
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