The FTP client uses a SOCKS configuration data set or file to determine whether to access a given FTP server directly or through a SOCKS server. The name of the data set or file is specified by coding the SOCKSCONFIGFILE statement in the client FTP.DATA file.

The FTP client references the SOCKSCONFIGFILE only when the FTP server is known to it by an IPv4 IP address or by a DNS name that resolves to an IPv4 IP address. The FTP client always connects directly to FTP servers known to it by IPv6 addresses or by DNS names that resolve to IPv6 addresses.

See z/OS Communications Server: IP Configuration Reference for details regarding the contents of the SOCKS configuration file.