private void write_tunnel_config() throws Exception
 {
	System.out.println("write_tunnel_config");


	String config = read_file(template_file);
	for (Iterator keys = props.keySet().iterator(); keys.hasNext(); )
	{
	 final String key = (String) keys.next();
	 final String val = props.getProperty(key);
	 config = replace_all(config, "${" + key + "}", val);
	}
	write_file(config_file, config);
 }