Listener UDP *:1024

[Mark.Andrews at nominum.com]

> 
> When I fire up named, it listens on these ports:
> 
> named       507  root    4u  IPv4    769       UDP *:1024 
> named       507  root   20u  IPv4    765       UDP localhost:domain 
> named       507  root   21u  IPv4    766       TCP localhost:domain
> (LISTEN)
> named       507  root   22u  IPv4    767       UDP 192.168.0.1:domain 
> named       507  root   23u  IPv4    768       TCP 192.168.0.1:domain
> (LISTEN)
> 
> Under these config options:
> 
> options {
>         listen-on { 127.0.0.1; 192.168/16; };
>         directory "/usr/local/named";
> };
> 
> Running this version:
> 
> bind-8.2.2_P5-9 on Linux 2.2.16
> 
> My question is, why does it listen to UDP *:1024 on all interfaces? 
> Unless it needs to, I don't want it to.  Can/should I tell it not to? 
> How?  I haven't logged any traffic to this port.  I can't find any
> reference to this in any of the docs.
> 
> Any ideas?

	A full service nameserver has both a server side (controled
	by listen-on) and a resolver side (controled by query-source).

	Named's resolver behaves like and other UDP client and
	picks a random (kernel assigned) port, by default, to issue
	its queries from and to listen for the answers to those
	queries.  It ignores answers that it is not expecting. It
	also including queries over this socket.

	Mark
> 
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> 
> John Hernandez, Network Engineer --------------------------------------
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> 
--
Mark Andrews, Nominum Inc.
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at nominum.com