[ntp:questions] Interface IP address Change.

kiran shirol kiran.shirol at gmail.com
Mon Jun 30 04:18:41 UTC 2008


Instead of using a polling approach, would it not be better we use a 
notification model, where in whenever there
is a change in the IP address a notification be generated from the interface 
managing module. I am not sure if
there is such a facility availble currently, I will check the same a get 

My point is , the probability of change in the IP address is low and hence 
periodic polling may not be the best
approach. Let me know your comments.


"Frank Kardel" <kardel at ntp.org> wrote in message 
news:4867F324.7080506 at ntp.org...
> David Woolley wrote:
>> Kiran Shirol wrote:
>>> In one of my setups with just one interface I had configured ntp server.
>>> Everything works fine till here. Now I change the IP address of the
>>> interface
>> Interface addresses aren't supposed to change, not just for ntp.  You 
>> will probably also confuse named.
>>> My question is How can I make NTP automatically detect this change and
>>> rebind
>>> upon the change in the IP address of the interface ?
> Since 4.2.4 ntpd detects changed interface addresses. Depending on the
> OS used this happens sooner or later. The fasted detection is on systems
> that have the routing socket interface (*BSD and maybe Solaris). For
> Windows and Linux interface scans are done every five minutes by default. 
> This default can be changed with the -U <secs between scans>
> command line switch for faster detects (60s is the current lower limit).
> If some good souls from the Linux and Windows communities would
> contribute the code needed the for fast detection on these systems 
> reaction time would improve there.
>> I believe some work has been done on working round broken ISPs who 
>> deliberately, or otherwise, misoperate DHCP.
> The dynamic interface update code was introduced in 4.2.4 to make
> ntpd work correctly in dynamic/mobile environments.
>   I'm not sure what state it
>> is in, but you should certainly be using the very latest release version, 
>> if not a development version.
> 4.2.4 (the current stable version) is just fine.
>> You are, of course, welcome to submit a patch to the source code.
> Frank 

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