This option enables you to control TLS support on the TELNET client. Negotiation of the arrangements for authentication is handled by TLS in this case to relieve the load on TELNET.
You enter the options for using TLS support in the option file(s) mentioned above as follows:
-Z <option>
Time when the options or changes to the options should become effective
After the TELNET 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 -Z OpenSSLLibname option (see "-Z OpenSSLlibName - Define an LMS file for an OpenSSL library") is only evaluated only once during a TELNET session, namely when the OpenSSL library is loaded. All other options become effective after the connection to the server has been set up.
Description of the -Z options
The -Z options are described below. The following must be observed here:
With the exception of the -Z tls-required option (see "-Z tls-required - Enable/disable TLS security on the TELNET client") all the -Z options can also be used for the AUTHENTICATION option (see "Option -A - Enable/disable AUTHENTICATION option"), provided TLS support is connected with the AUTHENTICATION option.
Parallel support of the START-TLS option (-Z tls-required) and AUTHENTICATION option (-A) is meaningless. When both of these options are specified the following error message is consequently issued:
Both START-TLS-Option and AUTHENTICATION-Option not allowedThe -Z OpenSSLlibName option (see "-Z OpenSSLlibName - Define an LMS file for an OpenSSL library") is also significant for supporting the ENCRYPTION option (see "Option -H -Enable/disable the ENCRYPTION option") as only encryption routines from this OpenSSL library are used.