FTPSssä

FTPSsä is the Swedish-language term used to refer to FTPS, the secure extension of the File Transfer Protocol (FTP) that adds cryptographic protection with TLS or SSL. It is distinct from SFTP, which is a different protocol based on SSH. FTPSsä can use two main operational modes: explicit FTPS (FTPES) and implicit FTPS. In explicit FTPS, the client negotiates TLS on the control channel after connecting, typically on port 21, and data channels may be protected as well. In implicit FTPS, TLS is required from the moment the connection is established, usually on port 990, with both control and data channels encrypted by default.

Data channel protection in FTPSsä is controlled by the PROT command, which selects whether the data channel is encrypted (P, for private) or left in the clear (C). The security of FTPSsä relies on valid certificates, proper certificate verification, and support for modern TLS versions. While explicit FTPS is generally more firewall-friendly, both modes require careful firewall and port-range configuration for the passive data connections they use.

FTPSsä is widely supported by both servers and clients. Popular server implementations include vsftpd, ProFTPD, and FileZilla Server, while clients such as FileZilla, WinSCP, and cURL provide FTPS support. It is commonly employed in enterprise environments where legacy FTP tooling must be retained but with encryption. Limitations include potential compatibility issues with some firewalls and NAT configurations, and the need for certificate management. As an alternative, SFTP (SSH File Transfer Protocol) is often preferred for simpler firewall traversal and integrated authentication.