(PECL ssh2 >= 0.9.0)
ssh2_fingerprint — Retrieve fingerprint of remote server
$session
   [, int $flags = SSH2_FINGERPRINT_MD5 | SSH2_FINGERPRINT_HEX
  ] )Returns a server hostkey hash from an active session.
sessionAn SSH connection link identifier, obtained from a call to ssh2_connect().
flags
       flags may be either of
       SSH2_FINGERPRINT_MD5 or
       SSH2_FINGERPRINT_SHA1 logically ORed with
       SSH2_FINGERPRINT_HEX or
       SSH2_FINGERPRINT_RAW.
      
Returns the hostkey hash as a string.
Example #1 Checking the fingerprint against a known value
<?php
$known_host = '6F89C2F0A719B30CC38ABDF90755F2E4';
$connection = ssh2_connect('shell.example.com', 22);
$fingerprint = ssh2_fingerprint($connection,
               SSH2_FINGERPRINT_MD5 | SSH2_FINGERPRINT_HEX);
if ($fingerprint != $known_host) {
  die("HOSTKEY MISMATCH!\n" .
      "Possible Man-In-The-Middle Attack?");
}
?>