Switch off ssl again with ftp after auth
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_FTP_SSL_CCC,
If enabled, this option makes libcurl use CCC (Clear Command Channel). It shuts down the SSL/TLS layer after authenticating. The rest of the control channel communication will be unencrypted. This allows NAT routers to follow the FTP transaction. Pass a long using one of the values below
Don't attempt to use CCC.
Do not initiate the shutdown, but wait for the server to do it. Do not send a reply.
Initiate the shutdown and wait for a reply.
Added in 7.16.1
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.