section req supported
  description   The supported request by the FTP daemon
  message ABOR abort previous command
  message ACCT specify account (ignored)
  message ADAT send an authentication protocol message
  message ALLO allocate storage (vacuously)
  message APPE append to a file
  message AUTH specify an authentication protocol to be performed
  message CCC set the command channel protection mode to 'Clear' (no protection). Only available if the -c command-line option was given.
  message CDUP change to parent of current working directory
  message CWD change working directory
  message DELE delete a file
  message ENC send a privacy and integrity protected command (given in argument)
  message HELP give help information
  message LIST give list files in a directory (''ls -lgA'')
  message MIC send an integrity protected command (given in argument)
  message MKD make a directory
  message MDTM show last modification time of file
  message MODE specify data transfer mode
  message NLST give name list of files in directory
  message NOOP do nothing
  message PASS specify password
  message PASV prepare for server-to-server transfer
  message PBSZ specify a protection buffer size
  message PORT specify data connection port
  message PROT specify a protection level under which to protect data transfers
  message PWD print the current working directory
  message QUIT terminate session
  message REST restart incomplete transfer
  message RETR retrieve a file
  message RMD remove a directory
  message RNFR specify rename-from file name
  message RNTO specify rename-to file name
  message SITE non-standard commands (see next section)
  message SIZE return size of file
  message STAT return status of server
  message STOR store a file
  message STOU store a file with a unique name
  message STRU specify data transfer structure
  message SYST show operating system type of server system
  message TYPE specify data transfer type
  message USER specify user name
  protocol FTP FTP - Protocol description.