IANA assigns port 1689 to firefox.
sudo ss -tlnp 'sport = :1689'sudo ss -ulnp 'sport = :1689'sudo lsof -nP -i :1689sudo netstat -tlnp | grep ':1689 'netstat -ano | findstr :1689Get-NetTCPConnection -LocalPort 1689 -State Listen | Select LocalAddress,OwningProcessnc -vz -w 5 HOST 1689Test-NetConnection HOST -Port 1689nc -vzu -w 5 HOST 1689sudo ufw deny 1689/tcpsudo iptables -A INPUT -p tcp --dport 1689 -j DROPsudo nft add rule inet filter input tcp dport 1689 dropNew-NetFirewallRule -DisplayName 'Block TCP 1689' -Direction Inbound -Protocol TCP -LocalPort 1689 -Action Blocksudo ufw deny 1689/udpsudo iptables -A INPUT -p udp --dport 1689 -j DROPsudo nft add rule inet filter input udp dport 1689 dropNew-NetFirewallRule -DisplayName 'Block UDP 1689' -Direction Inbound -Protocol UDP -LocalPort 1689 -Action BlockAll port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.