The TLS/SSL certificate used for FTPS is the same certificate that is used for your Files.com site's web portal. This applies to both implicit (port 990) and explicit (port 21) versions of FTPS. The certificate is updated and renewed automatically every 3 months, making it impractical to provide a documented fingerprint as it changes so frequently.

Our TLS/SSL certificates are always valid and fully chained. Your FTPS client will automatically verify the validity of certificates for you and will prompt you if an invalid certificate is found when making a connection.

If you want to verify a certificate's validity yourself then you can check the certificate by using an online SSL Checker, and pointing it at your Files.com site.

If you are using the Custom Domain feature, and are providing your own TLS/SSL certificate for your site, then the certificate you provided will be used for FTPS instead.

FTP client apps will check the fully qualified domain name (FQDN) of the presented TLS/SSL certificate against the name of the FTP site that is being connected to. If they do not match then the client will inform the user that this connection might not be secure. Make sure your FTP users are connecting to the same fully qualified domain name (FQDN) as defined in your TLS/SSL certificate.

Trust On First Use

FTPS users may receive a prompt such as The server's certificate is unknown. Please carefully examine the certificate to make sure the server can be trusted. when attempting to connect to a Files.com site using an FTP client such as FileZilla.

This usually means that this is the first time that the FTP client has attempted to connect to the Files.com site and doesn't represent an error or problem. The FTP client is presenting the user with the certificate details for informational purposes. This allows the user to visually inspect the certificate information and compare it to the FTP site that they are connecting to. The user is prompted to trust the certificate and, if trusted, will no longer be shown this prompt on subsequent connections.

Ideally, every FTP site should use valid and chained certificates, just like Files.com does, but some FTP sites continue to use self-signed certificates instead. Users should exercise caution when trusting self-signed certificates. Self-signed certificates should only be trusted when you personally trust the signer of the certificate yourself.

Many FTP clients use a Trust On First Use model where it will always prompt the user to accept every certificate, even if that certificate should be trusted anyway. Upon first connection attempt to every new site, this pop-up will display. The user can permanently trust the certificate so they don't get the same pop up the next time they connect to the same site.