CURLOPT_SSH_KNOWNHOSTS(3) Library Functions Manual CURLOPT_SSH_KNOWNHOSTS(3)
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.
DEFAULT
NULL
PROTOCOLS
This functionality affects scp and sftp
EXAMPLE
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode res;
curl_easy_setopt(curl, CURLOPT_URL, "sftp://example.com/file");
curl_easy_setopt(curl, CURLOPT_SSH_KNOWNHOSTS,
"/home/clarkkent/.ssh/known_hosts");
res = 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).
SEE ALSO
CURLOPT_SSH_AUTH_TYPES(3), CURLOPT_SSH_HOST_PUBLIC_KEY_MD5(3), CUR-
LOPT_SSH_HOST_PUBLIC_KEY_SHA256(3)
libcurl 2026-07-12 CURLOPT_SSH_KNOWNHOSTS(3)
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