PHP Manual: Retrieve fingerprint of remote server

Description

string ssh2_fingerprint(resource $session, int $flags = SSH2_FINGERPRINT_MD5 | SSH2_FINGERPRINT_HEX)

Returns a server hostkey hash from an active session.

Parameters

session: An 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.

Return Values

Returns the hostkey hash as a string.

Examples

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?");
}
?>