DDT - Dynamic DNS Tools

DDT stands for Dynamic Dns Tools. The goal of the project is to provide an
open and free (in the GPL-sense) set of tools that will permit the deployment
of secure and reliable dynamic DNS services.

There are three parts to Dynamic DNS Tools:
1) the DDT client daemon, ddtcd, and the DDT client utility, ddtc;
2) the DDT server daemon, ddtd, and the command line admin utility, ddta;
3) the CGI scripts used for web-based account registration and
   administration.

Here is a very brief and simple description of how DDT works:

1) The client sends an "update" query to the server. The query can either
   be an 'online' or an 'offline' update query.

2) The server marks the host online/offline by updating the back end
   database and the DNS server and sends an "update" reply to the client.

3) If the the host has been marked online, the server sends "alive"
   queries to the client at a rate of about once per minute. The client
   must reply to these "alive" queries. If the client does not reply to
   five queries in a row (five minutes), the server will mark the host
   offline. If the client does not hear from the server for five minutes,
   the client will send an "update" query to the server in an attempt to
   go online again. In other words, both the client and the server keep
   state information regarding each other. The server will not attempt
   reconnection; the client will.

DDT is Copyright (C) 2000 by Remi Lefebvre, Luca Filipozzi, and Benoit Joly

ddt is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

