UDP and "-m state --state xxx"? (Re: [suse-security] Looking for a secure time service)

Andreas Baetz wrote:

iptables -t filter -A INPUT -i <your interface> -m state -p udp [...] --state ESTABLISHED

There, you got me confused. I'm a freshman in the firewall arena, and although I can understand that "-m state --state xxx" makes sense with TCP (which opens and closes _directed_ connections actively), I don't know if and how this makes sense with UDP. If I'm not mistaken, UDP is undirected and has no notion of "NEW" or "ESTABLISHED", or has it? Mit freundlichen Grüssen / Regards Dipl. Inform. Ralph Seichter ISC Informatik Service & Consulting GmbH Tel +49 2241 867-0 mailto:r.seichter@isc-inf.com Fax +49 2241 867-222 http://www.isc-inf.com/