public static function closeMuxConnections()
    {
        $count = count(self::$multiplexedConnections);
        if ($count) {
            echo "Closing $count multiplexed connections...\n";
            foreach (self::$multiplexedConnections as $key => $connection) {
                exec("ssh -O stop -o LogLevel=QUIET -S $connection > /dev/null 2>&1");
                unset(self::$multiplexedConnections[$key]);
            }
        }
    }