IANA assigns port 1709 to centra.
sudo ss -tlnp 'sport = :1709'sudo ss -ulnp 'sport = :1709'sudo lsof -nP -i :1709sudo netstat -tlnp | grep ':1709 'netstat -ano | findstr :1709Get-NetTCPConnection -LocalPort 1709 -State Listen | Select LocalAddress,OwningProcessnc -vz -w 5 HOST 1709Test-NetConnection HOST -Port 1709nc -vzu -w 5 HOST 1709sudo ufw deny 1709/tcpsudo iptables -A INPUT -p tcp --dport 1709 -j DROPsudo nft add rule inet filter input tcp dport 1709 dropNew-NetFirewallRule -DisplayName 'Block TCP 1709' -Direction Inbound -Protocol TCP -LocalPort 1709 -Action Blocksudo ufw deny 1709/udpsudo iptables -A INPUT -p udp --dport 1709 -j DROPsudo nft add rule inet filter input udp dport 1709 dropNew-NetFirewallRule -DisplayName 'Block UDP 1709' -Direction Inbound -Protocol UDP -LocalPort 1709 -Action BlockAll port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.