2010/10/8 Enrico Tröger <[email protected]> > > On Sun, 3 Oct 2010 06:41:14 +1000, Amos wrote: > > >That's the way UDP works. > > Thanks so far. > But could you be so kind to explain it a little further? > I'm not that familiar with UDP and don't see why the clients need to > open a listening UDP port to send data to the server.
(Sorry, my previous reply was written on my mobile so it was short). For a reference, read a little about the UDP protocol - http://en.wikipedia.org/wiki/User_Datagram_Protocol Basically, the packet format calls for a "source port" which must be filled with a legitimate value. "man 7 udp" says: "In order to receive packets, the socket can be bound to a local address first by using bind(2). Otherwise the socket layer will automatically assign a free local port out of the range defined by /proc/sys/net/ipv4/ip_local_port_range and bind the socket to INADDR_ANY." I assume this happens when the first message is sent, if no port was assigned yet. So even if in this particular case there is only one-way traffic, the sender must have a port assigned to it. Hope this answers your question. --Amos _______________________________________________ collectd mailing list [email protected] http://mailman.verplant.org/listinfo/collectd
