CURLOPT_USE_SSL(3) Library Functions Manual CURLOPT_USE_SSL(3)
NAME
CURLOPT_USE_SSL - request using SSL / TLS for the transfer
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_USE_SSL, long level);
DESCRIPTION
Pass a long using one of the values from below, to make libcurl use your
desired level of SSL for the transfer.
These are all protocols that start out plain text and get "upgraded" to
SSL using the STARTTLS command.
This is for enabling SSL/TLS when you use FTP, SMTP, POP3, IMAP etc.
CURLUSESSL_NONE
do not attempt to use SSL.
CURLUSESSL_TRY
Try using SSL, proceed as normal otherwise. Note that server may
close the connection if the negotiation does not succeed.
CURLUSESSL_CONTROL
Require SSL for the control connection or fail with
CURLE_USE_SSL_FAILED.
CURLUSESSL_ALL
Require SSL for all communication or fail with
CURLE_USE_SSL_FAILED.
DEFAULT
CURLUSESSL_NONE
PROTOCOLS
This functionality affects ftp, imap, pop3 and smtp
EXAMPLE
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/dir/file.ext");
/* require use of SSL for this, or fail */
curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);
/* Perform the request */
curl_easy_perform(curl);
}
}
HISTORY
This option was known as CURLOPT_FTP_SSL up to 7.16.4. Supported by LDAP
since 7.81.0. Fully supported by the OpenLDAP backend only.
AVAILABILITY
Added in curl 7.17.0
RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error.
CURLE_OK (0) means everything was OK, non-zero means an error occurred,
see libcurl-errors(3).
SEE ALSO
CURLOPT_PROXY_SSLVERSION(3), CURLOPT_SSLVERSION(3), CURLOPT_SSL_OP-
TIONS(3)
libcurl 2026-07-12 CURLOPT_USE_SSL(3)
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