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CURLOPT_LOGIN_OPTIONS(3) Library Functions Manual CURLOPT_LOGIN_OPTIONS(3)

NAME

CURLOPT_LOGIN_OPTIONS - login options

SYNOPSIS

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

DESCRIPTION

Pass a char pointer as parameter, which should be pointing to the null-terminated options string to use for the transfer.

For more information about the login options please see RFC 2384, RFC 5092 and the IETF draft draft-earhart-url-smtp-00.txt.

CURLOPT_LOGIN_OPTIONS(3) can be used to set protocol specific login options, such as the preferred authentication mechanism via "AUTH=NTLM" or "AUTH=*", and should be used in conjunction with the CURLOPT_USERNAME(3) option.

Since 8.2.0, IMAP supports the login option "AUTH=+LOGIN". With this option, curl uses the plain (not SASL) LOGIN IMAP command even if the server advertises SASL authentication. Care should be taken in using this option, as it sends your password in plain text. This does not work if the IMAP server disables the plain LOGIN (e.g. to prevent password snooping).

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

Using this option multiple times makes the last set string override the previous ones. Set it to NULL to disable its use again.

CURLOPT_LOGIN_OPTIONS(3) is a login property, it does not change the security context. This means that this option changes how the login happens when a connection is created, but it does not affect which connections libcurl can reuse. libcurl may reuse a connection that was set up with a different options string; a different options string does not by itself prevent reuse. Connection reuse still depends on other connection properties matching, such as the protocol, hostname, port number, credentials and other settings that affect the connection.

DEFAULT

NULL

PROTOCOLS

This functionality affects imap, ldap, pop3 and smtp

EXAMPLE

int main(void)
{

CURL *curl = curl_easy_init();
if(curl) {
CURLcode result;
curl_easy_setopt(curl, CURLOPT_URL, "smtp://example.com/");
curl_easy_setopt(curl, CURLOPT_LOGIN_OPTIONS, "AUTH=*");
result = curl_easy_perform(curl);
curl_easy_cleanup(curl);
} }

HISTORY

Support for OpenLDAP added in 7.82.0.

AVAILABILITY

Added in curl 7.34.0

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_PASSWORD(3), CURLOPT_USERNAME(3)

2026-04-23 libcurl