Security Considerations

The FTP Server listener supports secure transfer using the FTP/S protocol as defined in RFC 2228 and RFC 4217. It supports the FEAT request from standard FTP clients and accepts requests to initiate operations on secure channels. Security control is done by the client. Configuration can be set to reject clients that do not request security operations. Secure control channels and data transfer channels are treated separately. For example, if the listener configuration does not require that secure data transfer be done, then the listener will accept client requests to transfer files securely if appropriate keystores are defined, but will accept transfers on non-secure channels. If the security configuration is not provided, the FEAT response to the client will not indicate support for TLS channels.

The server uses the keystore of the system, which is defined in the system properties. If a keystore is not defined, the server rejects the attempt of the client to establish a secure channel.

Minimum levels of security are configured for the listener, preventing socket negotiation below the specified levels.

The server implements data transfer port theft protection requiring that the data transfer socket be connected to the same IP address as the control socket.

Access permissions for directories can be configured on a per-user basis in the security file. Additionally, access from specific hosts can be specified on a per-user basis in the security file. This restricts the user to known client equipment. The client can be specified as a host name or as an IP address. The test is not case-sensitive. For more information, see The Security File.