MDA - internet/ftp/ftp

Comment:: protocol for obtaining and uploading files over the Internet (bi-directional file transfer)
invocation: open a connection: ftp
Comment:: uses separate connections for data transfer and control commands
Comment:: runs on top of TCP/IP; default server port 21 (for sending commands) and 20 (data transfer)
drawback: password and data in clear -- very hard to get through firewall securely

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