CURLOPT_FTP_ALTERNATIVE_TO_USER(3) Library Functions Manual CURLOPT_FTP_ALTERNATIVE_TO_USER(3)

CURLOPT_FTP_ALTERNATIVE_TO_USER - command to use instead of USER with FTP

#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_FTP_ALTERNATIVE_TO_USER,
                          char *cmd);

Pass a char pointer as parameter, pointing to a string which is used to authenticate if the usual FTP "USER user" and "PASS password" negotiation fails. This is currently only known to be required when connecting to Tumbleweed's Secure Transport FTPS server using client certificates for authentication.

The application does not have to keep the string around after setting this option.

NULL

This functionality affects ftp only

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/foo.bin");
    curl_easy_setopt(curl, CURLOPT_FTP_ALTERNATIVE_TO_USER, "two users");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

Added in curl 7.15.5

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).

CURLOPT_FTP_ACCOUNT(3), CURLOPT_FTP_SKIP_PASV_IP(3), CURLOPT_SERVER_RESPONSE_TIMEOUT(3), CURLOPT_USERNAME(3)

2025-02-13 libcurl