---
name: "CURLOPT_SSH_HOST_PUBLIC_KEY_MD5"
section: "3"
platform: "macos"
package: "curl"
version: "166.0.0.0.1"
release: "macOS 26.5"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_SSH_HOST_PUBLIC_KEY_MD5"
---

# CURLOPT\_SSH\_HOST\_PUBLIC\_KEY\_MD5(3)

MD5 checksum of SSH server public key

## NAME

CURLOPT\_SSH\_HOST\_PUBLIC\_KEY\_MD5 - MD5 checksum of SSH server public key

## SYNOPSIS

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

## DESCRIPTION

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)](/CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256/3.md)* instead.

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

## DEFAULT

NULL

## PROTOCOLS

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

## AVAILABILITY

Added in 7.17.1

## RETURN VALUE

Returns CURLE\_OK if the option is supported, CURLE\_UNKNOWN\_OPTION if not, or CURLE\_OUT\_OF\_MEMORY if there was insufficient heap space.

## SEE ALSO

[**CURLOPT\_SSH\_AUTH\_TYPES**(3)](/CURLOPT_SSH_AUTH_TYPES/3.md), [**CURLOPT\_SSH\_HOST\_PUBLIC\_KEY\_SHA256**(3)](/CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256/3.md), [**CURLOPT\_SSH\_KNOWNHOSTS**(3)](/CURLOPT_SSH_KNOWNHOSTS/3.md), [**CURLOPT\_SSH\_PUBLIC\_KEYFILE**(3)](/CURLOPT_SSH_PUBLIC_KEYFILE/3.md)