File Transfer Protocol (FTP) server

An FTP server is a socket application that is called by the Internet Daemon when a message is received on well-known port 21. The FTP server is started by the Internet Daemon and then communicates with the remote node directly.

The FTP server establishes two connections between the client and server processes; one connection for control information (commands and responses), and the other connection for the data that is transferred. The FTP server can handle both binary and text files. The files can be transferred in both directions.

The FTP client on the remote host is prompted for access information, such as the login name and password (if required), on the remote system.

The FTP server authenticates users according to the following rules:

  • The login name must be in the etc/passwd database and cannot be a null password. A password must be provided by the client before any file operations can be performed.
  • The login name must not be in the etc/ftpusers file.
  • If the user name is anonymous or ftp, an anonymous ftp account must be present in the password file (the (user ftp). You are allowed to log in by specifying any password. By convention, use an email address for the user as the password.
  • If file system security is enabled and system generation option OPSEC is set on, you cannot log in by using the user name anonymous or ftp and any password. Instead, you must use a valid user ID and password that is defined in the file system. See the z/TPF Database User's Guide for more information about file system security.
The FTP server on z/TPF does not have Transport Layer Security (TLS) support. To transfer sensitive data in a production environment, use one of the following alternative methods:
  • Use Java-based FTP packages to securely transfer files into and out of the z/TPF system.
  • Use the FTP client on z/TPF that supports TLS sessions.
  • Use the standard TPF loader process that is not FTP-based, for example, general data set (GDS) and tape.