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Port 12009 (ghvpn)

IANA assigns port 12009 to ghvpn: Green Hills VPN.

Registered (user) port, 1024-49151 UDP

Port 12009 is normally used over UDP; the checker tests TCP only, so a "filtered" result does not mean the UDP service is down.

IANA assignment

Service nameProtoDescriptionAssigneeReference
ghvpn UDP Green Hills VPN Green Hills Software -

Registry dates for this port: registered 2012-02-07.

Check what is listening on port 12009

Linux: UDP 12009
sudo ss -ulnp 'sport = :12009'
Linux / macOS: which process owns the port
sudo lsof -nP -i :12009
Windows (Command Prompt)
netstat -ano | findstr :12009
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 12009

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 12009

Block port 12009 in the firewall

ufw
sudo ufw deny 12009/udp
iptables
sudo iptables -A INPUT -p udp --dport 12009 -j DROP
nftables
sudo nft add rule inet filter input udp dport 12009 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 12009' -Direction Inbound -Protocol UDP -LocalPort 12009 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.