IANA assigns port 21590 to vofr-gateway: VoFR Gateway.
sudo ss -tlnp 'sport = :21590'sudo ss -ulnp 'sport = :21590'sudo lsof -nP -i :21590sudo netstat -tlnp | grep ':21590 'netstat -ano | findstr :21590Get-NetTCPConnection -LocalPort 21590 -State Listen | Select LocalAddress,OwningProcessnc -vz -w 5 HOST 21590Test-NetConnection HOST -Port 21590nc -vzu -w 5 HOST 21590sudo ufw deny 21590/tcpsudo iptables -A INPUT -p tcp --dport 21590 -j DROPsudo nft add rule inet filter input tcp dport 21590 dropNew-NetFirewallRule -DisplayName 'Block TCP 21590' -Direction Inbound -Protocol TCP -LocalPort 21590 -Action Blocksudo ufw deny 21590/udpsudo iptables -A INPUT -p udp --dport 21590 -j DROPsudo nft add rule inet filter input udp dport 21590 dropNew-NetFirewallRule -DisplayName 'Block UDP 21590' -Direction Inbound -Protocol UDP -LocalPort 21590 -Action BlockAll port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.