CURLOPT_FTPSSLAUTH(3)

CURLOPT_FTPSSLAUTH3

Order in which to attempt tls vs ssl

Usage

#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_FTPSSLAUTH, long order);

Overview

Pass a long using one of the values from below, to alter how libcurl issues "AUTH TLS" or "AUTH SSL" when FTP over SSL is activated. This is only interesting if CURLOPT_USE_SSL(3) is also set.

Possible order values:

CURLFTPAUTH_DEFAULT

Allow libcurl to decide.

CURLFTPAUTH_SSL

Try "AUTH SSL" first, and only if that fails try "AUTH TLS".

CURLFTPAUTH_TLS

Try "AUTH TLS" first, and only if that fails try "AUTH SSL".

Default

CURLFTPAUTH_DEFAULT

Protocols

This functionality affects ftp only

Examples

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/file.txt");
    curl_easy_setopt(curl, CURLOPT_USE_SSL, CURLUSESSL_TRY);
    /* funny server, ask for SSL before TLS */
    curl_easy_setopt(curl, CURLOPT_FTPSSLAUTH, CURLFTPAUTH_SSL);
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

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).

Releases

7 releases since Debian 8 (Jessie); the text changed 6 times.

  1. 8
  2. 9
  3. 10
  4. 11
  5. 12
  6. 13
  7. Arch

History

CURLFTPAUTH_* enums became long types in 8.16.0, prior to this version a long cast was necessary when passed to curl_easy_setopt(3).

Availability

Added in curl 7.12.2

From curl 8.23.0-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.