File transfer protocol uses two TCP Port. One port is for control while the other is for data transfers. It is basically a protocol which is command-response in nature. For maintaining the session, the control port makes usage of telnet protocol. FTP operates in both active and passive modes. Due to variety in operating systems and hardware types, files are converted to neutral data types at the time of transport and then at the destination, it is again converted to local type. Different types of neutral data types are ASCII, EBCDIC, IMAGE and LOCAL. It is the responsibility of the client to communicate to the server that which data type is to be used. If no datatype is specified, then ASCII is the default data type. In an operating system, files are stored in different structures which are well defined by file transfer protocol. Different structures are File(F) is a byte sequence, Record(R) is a series of records and Page(P) is a series of pages. The default one is File(F).