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ssh2_fingerprint

(PECL ssh2 >= 0.9.0)

ssh2_fingerprint — Retrieve fingerprint of remote server

Description

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

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?");
}
?>

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User Contributed Notes 1 note

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-16

Lyle Mantooth ¶

10 years ago


If you're going to compare the fingerprint to a user-submitted form field, it's probably a good idea to do case-insensitive comparison:
<?php

if ($conn = ssh2_connect($user, $password)) {
    $fingerprint = ssh2_fingerprint($conn);
    if (strcasecmp($fingerprint, $known_value) === 0) {
        // Do your thing.
    }
}
?>
Of course, this is only necessary when you use the SSH2_FINGERPRINT_HEX option, not SSH2_FINGERPRINT_RAW.

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