/* FTP Commands *************************************************************/
/* Command summary:
*
* ABOR - abort a file transfer
* ACCT - send account information
* APPE - append to a remote file
* CDUP - CWD to the parent of the current directory
* CWD - change working directory
* DELE - delete a remote file
* HELP - return help on using the server
* LIST - list remote files
* MDTM - return the modification time of a file
* MKD - make a remote directory
* MLSD - Standardized directory listing (instead of LIST)
* MLST - Standardized object listing (instead of LIST)
* MODE - set transfer mode
* NLST - name list of remote directory
* NOOP - do nothing
* PASS - send password
* PASV - enter passive mode
* PORT - open a data port
* PWD - print working directory
* QUIT - terminate the connection
* REIN - reinitialize the connection
* RETR - retrieve a remote file
* REST - Sets the point at which a file transfer should start
* RMD - remove a remote directory
* RNFR - rename from
* RNTO - rename to
* SITE - site-specific commands
* SIZE - return the size of a file
* STOR - store a file on the remote host
* STOU - store a file uniquely
* STRU - set file transfer structure
* STAT - return server status
* SYST - return system type
* TYPE - set transfer type
* USER - send username
*
/* FTP Replies **************************************************************/
*
* 110 - Restart marker reply.
* 120 - Service ready in nnn minutes.
* 125 - Data connection already open; transfer starting.
* 150 - File status okay; about to open data connection.
* 200 - Command okay.
* 202 - Command not implemented, superfluous at this site.
* 211 - System status, or system help reply.
* 212 - Directory status.
* 213 - File status.
* 214 - Help message.
* 215 - NAME system type.
* 220 - Service ready for new user.
* 221 - Service closing control connection.
* 225 - Data connection open; no transfer in progress.
* 226 - Closing data connection.
* 227 - Entering Passive Mode (h1,h2,h3,h4,p1,p2).
* 230 - User logged in, proceed.
* 250 - Requested file action okay, completed.
* 257 - "PATHNAME" created.
* 331 - User name okay, need password.
* 332 - Need account for login.
* 350 - Requested file action pending further information.
* 421 - Service not available, closing control connection.
* 425 - Can't open data connection.
* 426 - Connection closed; transfer aborted.
* 450 - Requested file action not taken.
* 451 - Requested action aborted: local error in processing.
* 452 - Requested action not taken.
* 500 - Syntax error, command unrecognized.
* 501 - Syntax error in parameters or arguments.
* 502 - Command not implemented.
* 503 - Bad sequence of commands.
* 504 - Command not implemented for that parameter.
* 530 - Not logged in.
* 532 - Need account for storing files.
* 550 - Requested action not taken.
* 551 - Requested action aborted: page type unknown.
* 552 - Requested file action aborted.
* 553 - Requested action not taken.
*/
