[ntp:questions] Autokey and Dynamic IPs

Danny Mayer mayer at ntp.isc.org
Fri Jan 11 03:11:12 UTC 2008

Steve wrote:
> Hi,
> I am using NTP 4.2.0 and am planning to use Autokey (IFF) between a
> distributed client base (a large population) and some centralized
> servers. However my client base will use DHCP and therefore may change
> their IP.
> What is expected to happen when client IP changes while running NTP
> Autokey? I am concerned that it will lose sync because of the IPs used
> in the session keys.
> What is the recommendation on how to deal with DHCP when using
> autokey? Can I just restart the daemon on the client to handle this
> case and re-obtain autokey'd sync?
> Is there anything the server needs to do when the IP changes on the
> client in order to let that client resynch with its new IP? I hope the
> server is not effected by this.
> thanks!
> Steve

Upgrade to 4.2.4 to get dynamic IP support. Don't use NAT in the network 
configuration as Autokey cannot work with it. When the IP address 
changes ntpd notices (or checks every 10 minutes) and updates the 
configuration information and restarts the association and needs to 
reauthenticate with Autokey. This all should work properly.


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