curl/docs/libcurl/opts/CURLOPT_SSH_PRIVATE_KEYFILE.md
Daniel Stenberg f3c11692a9
CURLOPT_SSH_*_KEYFILE: used for setting up, then no more
So changing them after the connection is made still allows libcurl to
reuse the existing connections.

Reported-by: Bigtang on hackerone
Closes #22211
2026-06-29 14:34:34 +02:00

2 KiB

c SPDX-License-Identifier Title Section Source See-also Protocol Added-in
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. curl CURLOPT_SSH_PRIVATE_KEYFILE 3 libcurl
CURLOPT_SSH_AUTH_TYPES (3)
CURLOPT_SSH_PUBLIC_KEYFILE (3)
SFTP
SCP
7.16.1

NAME

CURLOPT_SSH_PRIVATE_KEYFILE - private key file for SSH auth

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSH_PRIVATE_KEYFILE,
                          char *filename);

DESCRIPTION

Pass a char pointer pointing to a filename for your private key. If not used, libcurl defaults to $HOME/.ssh/id_rsa or $HOME/.ssh/id_dsa if the HOME environment variable is set, and in the current directory if HOME is not set.

If the file is password-protected, set the password with CURLOPT_KEYPASSWD(3).

The SSH library derives the public key from this private key when possible. If the SSH library cannot derive the public key from the private one and no public one is provided with CURLOPT_SSH_PUBLIC_KEYFILE(3), the transfer fails.

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

This option is used to set up a new connection only. The private key is used when libcurl establishes a new SSH connection; once that connection has been successfully set up and verified, it is deemed vetted and may be reused by libcurl even if this option is changed.

DEFAULT

As explained above

%PROTOCOLS%

EXAMPLE

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "sftp://example.com/file");
    curl_easy_setopt(curl, CURLOPT_SSH_PRIVATE_KEYFILE,
                     "/home/clarkkent/.ssh/id_rsa");
    curl_easy_setopt(curl, CURLOPT_KEYPASSWD, "password");
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

%AVAILABILITY%

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).