[ntp:questions] Kiss-O'-Death

Danny Mayer mayer at ntp.isc.org
Thu Jun 26 02:23:16 UTC 2008

Bob wrote:
> How exactly do you configure NTP to send a KOD? I'm running Meinberg's port 
> under Win XP. I'm a sever in the pool. I've got two remote clients that are 
> querying at a rate of several times a minute. Sometimes their queries are 
> spaced wider, but sometimes they hit me spaced at only a few seconds apart. 
> I can block them in my router, but they'd still be sending traffic my way. 
> I'd like to see if KOD makes them go away.  Reading the docs, it appears 
> that I need to mod ntp.conf and add restrict x.x.x.x kod, but then I'd need 
> to restart the service.
> Thanks for any help. 

Let me give you the bad news: If they are hitting your server that 
frequently then they are most probably not running ntpd and only ntpd as 
far as I know, takes notice of KOD packets. There is a newer version in 
ntp-dev which will in a KOD basically return the same timestamp that was 
sent and if the client is obeying the rules it will cause the client 
which is ignoring the KOD signal to misinterpret and reset the clock to 
be further away from the existing time on your ntpd server so that each 
time it tries it gets further and further away in ever increasing 
amounts. When the clock is so far off that someone notices they will 
probably stop using your servers. Meinberg has not released a copy of 
that version since it's still development code. Maybe we can make you a 
binary which you could just drop into the directory where you keep 
ntpd.exe. We will then see if that works for you. I would make an 
excellent test. I assume you do not know whose machines belong to?


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