(PECL ssh2 >= 0.9.0)
ssh2_fingerprint — Retrieve fingerprint of remote server
$session
[, int $flags = SSH2_FINGERPRINT_MD5 | SSH2_FINGERPRINT_HEX
] ) : stringReturns 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 != $known_host) {
die("HOSTKEY MISMATCH!\n" .
"Possible Man-In-The-Middle Attack?");
}
?>
If you're going to compare the fingerprint to a user-submitted form field, it's probably a good idea to do case-insensitive comparison:
<?php
if ($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.