Parameter selection using option files

Settings which are particularly important for using TLS are stored in one or more option files. The option file is read in when the FTP client is started. However, you can also adapt the option setting to suit current requirements later by reading in an option file with the FTP client command readopt (see "readopt - Read in option file").

Determination of the relevant option file by the FTP client

The FTP client proceeds as follows to determine the relevant option files:

1. First the FTP client searches for a centrally stored option file with the default file name $.SYSDAT.TCP-IP-AP.nnn.F-GOPT

   In the event of installation with IMON the system administrator can redefine the logical ID SYSDAT.F-GOPT to refer to another file which the FTP client then uses as option file.

2. Regardless of the central file named under 1.), the FTP client also searches for a userowned option file under the name SYSDAT.TCP-IP-AP.nnn.FTP.OPT. If this file exists, the FTP client reads the options from there.

If an option is included in both files but with different values, the value defined in the userowned file applies.

If settings for TLS security have been specified using the FTP client command, these have priority over those specified in the option file.

Details of the special aspects relating to TLS support of the FTP client in POSIX are provided on "FTP client in POSIX".

Notation of the options in the option file

The various options must be entered in the option file according to the following rules:

• Each option must be in a separate line.

• If an option’s arguments extend over more than one line, each line that is to be continued must be terminated with the continuation character “\”.

• A line beginning with the character “#” in column 1 is ignored when the file is read in.

• The option names are not case-sensitive.

Time when the options or changes to the options become effective

After the FTP client has started up you can read in the required option file using the client command readopt (see "readopt - Read in option file"). You can repeat this procedure as often as you wish.

The individual options or changes to the options become effective at different times:

• With the following options the changes take effect the next time a control connection is set up:

  -protect
  -private
  -tlsCipherSuite
  -tlsKeyFile
  -tlsCertificateFile
  -tlsProtocol
  -tlsCACertificateFile
  -tlsCARevocationFile
  -tlsVerifyServer
  -tlsVerifyDepth
  -tlsRandomSeed

• The following option is only evaluated once during an FTP session, namely when the OpenSSL library is loaded
  (Message: [Loading OpenSSL library...]):

  -tlsOpenSSLlibName

  If you wish to set up a connection to other value of this option after TLS has been initialized, proceed as follows:

  1. Terminate FTP client

  2. Adapt default option file if required

  3. Restart FTP client

  4. Before starting TLS initialization with a protect, private or open command:

     If required, read in a suitable option file using the readopt command

  Steps 2.) and 4.) are alternatives.

Description of the options

The individual options are described below.