CURLOPT_FTP_USE_EPSV - enable/disable use of EPSV
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_FTP_USE_EPSV, long epsv);
as a long. If the value is 1, it tells curl to use the EPSV
command when doing passive FTP downloads (which it does by default). Using
EPSV means that it will first attempt to use EPSV before using PASV, but if
you pass zero to this option, it will not try using EPSV, only plain PASV.
If the server is an IPv6 host, this option will have no effect as of 7.12.3.
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/old-server/file.txt");
/* let's shut off this modern feature */
curl_easy_setopt(curl, CURLOPT_FTP_USE_EPSV, 0L);
ret = curl_easy_perform(curl);
Along with FTP
Returns CURLE_OK if FTP is supported, and CURLE_UNKNOWN_OPTION if not.