Tribblix: manual page: CURLOPT_SSH

CURLOPT_SSH_KNOWNHOSTS(3) Introduction to Library Functions

NAME

CURLOPT_SSH_KNOWNHOSTS - filename holding the SSH known hosts

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSH_KNOWNHOSTS, char *fname);

DESCRIPTION

Pass a pointer to a null-terminated string holding the filename of
the known_host file to use. The known_hosts file should use the
OpenSSH file format. If this file is specified, libcurl only accepts
connections with hosts that are known and present in that file, with
a matching public key. Use CURLOPT_SSH_KEYFUNCTION(3) to alter the
default behavior on host and key matches and mismatches.

We strongly suggest users doing SCP or SFTP transfers to set this
option to make sure that the network communication is done with the
intended server and not an impostor.

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.

This option is only consulted when libcurl establishes a new
connection. Once a connection has been created and its host key
verified against the known hosts file, it is deemed vetted and may be
reused by libcurl without re-running the known hosts check, even if
you later change SSH host verification options (including setting
this option to NULL or using CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256(3) or
CURLOPT_SSH_HOST_PUBLIC_KEY_MD5(3)). Such changes only affect
subsequently created connections; existing cached connections can
continue to be reused with the verification that was in effect when
they were first established. If you need to force re-verification
with the new settings, use CURLOPT_FRESH_CONNECT(3) or
CURLOPT_FORBID_REUSE(3) to avoid reusing the old connection.

DEFAULT

NULL

PROTOCOLS

This functionality affects scp and sftp

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_KNOWNHOSTS,
"/home/clarkkent/.ssh/known_hosts");
result = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}

AVAILABILITY

Added in curl 7.19.6

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).