additional udp port open

[Jim Reid]

>>>>> "Barry" == Barry Margolin <barmar at bbnplanet.com> writes:

    Barry> In article <23098.945889893 at gromit.rfc1035.com>, Jim Reid
    Barry> <jim at rfc1035.com> wrote:
    >>>>>>> "Bobi" == Bobi <bobi at techno-link.com> writes:
    >>
    Bobi> Is it nomal for named 8.2.2 to listen on additional, random
    Bobi> udp port?
    >>  No. Definitely not. However it is normal for BIND8 name
    >> servers to use a random, non-privileged port for *sending*
    >> queries to other name servers.

    Barry> Which implies that it's normal for it to listen on that
    Barry> port.  Since UDP is connection-less, named must listen on
    Barry> the source port used for outbound queries.

True, but the name server is not listening on that port for incoming
queries. It only expects that port to receive answers to the queries
it has sent. If a query is sent to this port, an error is logged -
"refused query on non-query socket" - and the query is dropped.