[ntp:questions] Re: sendto( Invalid argument

David Woolley david at djwhome.demon.co.uk
Sat Aug 13 08:14:38 UTC 2005

In article <hmvidd.pdc.ln at barnabe.home.fr>, Edrusb <edrusba at free.fr> wrote:

> - What is the use of this wildcard UDP socket (it does not seems used)?

Handles incoming requests?

> - Why does ntpd uses theses UDP specific interfaces sockets, while the
> configuration file does not specify any interface to listen on or to not
> listen on?

I believe this is because the security features require the origin
address to be known by the sender (possibly only for servers).

> - How to have ntpd be able to work with a dialup link?

NTP is not designed for use over intermittent connections.  The real
reason that this interface address problem is an issue is that some
low cost broadband suppliers deliberately mis-operate DHCP to make
their customers' IP addresses unstable and prevent them running servers
on home user accounts.

What I do with intermittent connections is to trim out the static
component of the frequency error using ntptime and tickadj and then
occassionally re-correct the phase using ntpdate, making sure that I
do it when the line is idle.

> Any help is (very) welcome. :-)

As noted elsewhere, you can do IP address masquerading down stream so that
ntpd sees a fixed address.

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