IANA assigns port 1725 to iden-ralp.
sudo ss -tlnp 'sport = :1725'sudo ss -ulnp 'sport = :1725'sudo lsof -nP -i :1725sudo netstat -tlnp | grep ':1725 'netstat -ano | findstr :1725Get-NetTCPConnection -LocalPort 1725 -State Listen | Select LocalAddress,OwningProcessnc -vz -w 5 HOST 1725Test-NetConnection HOST -Port 1725nc -vzu -w 5 HOST 1725sudo ufw deny 1725/tcpsudo iptables -A INPUT -p tcp --dport 1725 -j DROPsudo nft add rule inet filter input tcp dport 1725 dropNew-NetFirewallRule -DisplayName 'Block TCP 1725' -Direction Inbound -Protocol TCP -LocalPort 1725 -Action Blocksudo ufw deny 1725/udpsudo iptables -A INPUT -p udp --dport 1725 -j DROPsudo nft add rule inet filter input udp dport 1725 dropNew-NetFirewallRule -DisplayName 'Block UDP 1725' -Direction Inbound -Protocol UDP -LocalPort 1725 -Action BlockAll port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.