Jan 311999

Getting DCC to work with natd

DCC is and IRC Protocol and is an acroynm for Direct Client to Client protocol.   DCC allows two IRC users to chat and/or send files directly with each other instead of passing the data through the server.  It is a more efficient use of resources than a normal chat window.

The way DCC Chat works often means it does notwork if  you are behind a firewall.   This is not the fault of the firewall, but rather it is a consequence of the DCC chat protocol.  The problem stems from the IP address translation which often occurs as the traffic passes through the firewall.  This translation is known as NAT or Network Address Translation.  The symptoms of the problem are an inability to send files with DCC but you are able to receive files.

To get around this problem, I’ve decided to try and install an IRC Proxy which will get around the problem.

natd options

If you are using natd, then I’ve been told that using the following options will allow DCC to work.  Please note that I’m now running ipfilter and I’ve not tested these options.   If you find that they work for you, please let me know.

The following is an extract from the man natd pages:

-use_sockets | -s
 Allocate a socket(2) in order to establish an FTP data or IRC
 DCC send connection.  This option uses more system resources,
 but guarantees successful connections when port numbers con