CURLOPT_SSH_HOST_PUBLIC_KEY_MD5 - MD5 checksum of SSH server public key

Added in curl 7.17.1

NULL

Pass a char pointer pointing to a string containing 32 hexadecimal digits. The string should be the 128 bit MD5 checksum of the remote host's public key, and libcurl aborts the connection to the host unless the MD5 checksum match. MD5 is a weak algorithm. We strongly recommend using CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256(3) instead. 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.

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_HOST_PUBLIC_KEY_MD5, "afe17cd62a0f3b61f1ab9cb22ba269a7"); res = curl_easy_perform(curl); curl_easy_cleanup(curl); } }

CURLOPT_SSH_HOST_PUBLIC_KEY_MD5 - MD5 checksum of SSH server public key

This functionality affects scp and sftp

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_SSH_AUTH_TYPES(3), CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256(3), CURLOPT_SSH_KNOWNHOSTS(3), CURLOPT_SSH_PUBLIC_KEYFILE(3) libcurl 2025-06-16 CURLOPT_SSH_HOST_PUBLIC_KEY_MD5(3)

#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSH_HOST_PUBLIC_KEY_MD5, char *md5);