[ntp:questions] UDP 123 Port restriction

Chris Albertson albertson.chris at gmail.com
Fri Feb 11 23:58:12 UTC 2011


On Wed, Feb 9, 2011 at 1:20 AM, Chandan Laskar <Chandan.Laskar at itc.in> wrote:
>
> Hi,
>
> We are planing to deploy Network Time Server in our Organization.
>
> According to the architecture , Stratum 2 server will be responsible to
> provide correct time to Stratum 3 server and client ( Other servers) will
> synchronize with Stratum 3 server for obtaining correct time. Stratum 2
> server will synchronize with Stratum 1  server.
>
> We will use NTP 4.2.6p3
>
> Is it mandatory to open UDP port 123  between Stratum 2 and Stratum 3

Between servers that you control you had build ntpd to use any port
you like.  But of course to comunicate with servers outside your
control you have touse the agreed to port.   At soe point to will need
a ntpd server tat faces both ways to "pool" servers on the Internet on
port 123 and to your internal servers.  This server will need to
listen on bth 123 and your custom port number.

Now the question is "Why?"  what is the reason for not using 123?

Broadcast might solve this problem.  If you can use broadcast then you
are not using 123.  But again what is the big picture, what is the
problem to be solved by all o this?
-- 
=====
Chris Albertson
Redondo Beach, California



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