Using Windows Firewall with secure FTP over SSL (FTPS) traffic Now that we have successfully configured our FTP server for secure FTP over SSL (FTPS) we need to configure our Windows Firewall because the default settings do not allow traffic. Normally you would open port 21 for FTP traffic but because we configured our server for Secure FTP there are more steps involved. The stateful FTP packet inspection in Windows Firewall will most likely prevent SSL from working because Windows Firewall filter for stateful FTP inspection will not be able to parse the encrypted traffic that would establish the data connection. ftp, ssl, port 21 Read More