IANA assigns port 1620 to faxportwinport.
sudo ss -tlnp 'sport = :1620'sudo ss -ulnp 'sport = :1620'sudo lsof -nP -i :1620sudo netstat -tlnp | grep ':1620 'netstat -ano | findstr :1620Get-NetTCPConnection -LocalPort 1620 -State Listen | Select LocalAddress,OwningProcessnc -vz -w 5 HOST 1620Test-NetConnection HOST -Port 1620nc -vzu -w 5 HOST 1620sudo ufw deny 1620/tcpsudo iptables -A INPUT -p tcp --dport 1620 -j DROPsudo nft add rule inet filter input tcp dport 1620 dropNew-NetFirewallRule -DisplayName 'Block TCP 1620' -Direction Inbound -Protocol TCP -LocalPort 1620 -Action Blocksudo ufw deny 1620/udpsudo iptables -A INPUT -p udp --dport 1620 -j DROPsudo nft add rule inet filter input udp dport 1620 dropNew-NetFirewallRule -DisplayName 'Block UDP 1620' -Direction Inbound -Protocol UDP -LocalPort 1620 -Action BlockAll port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.