function sftp($local_file, $remote_file)
{
$this->log->verbose("sftp'ing {$local_file} to {$remote_file}");
$sftp = ssh2_sftp($this->conn);
$remote = fopen("ssh2.sftp://{$sftp}{$remote_file}", 'w');
$local = fopen($local_file, "r");
$ret = stream_copy_to_stream($local, $remote);
return $ret;
}