[ntp:questions] Max number of lines that ntpdc -c monlist could display

Spoon devnull at localhost.com
Mon May 7 08:06:24 UTC 2007

Harlan Stenn wrote:

> Eugen COCA wrote:
>> What is the maximum number of lines that ntpdc -c monlist
>> command could display ?
> I *think* the answer is somewhere between 400 and 600.  It has to do with
> the number of responses that will fit into a UDP packet.
>> Are there any ways to "correct" this limmitation only by modifying
>> the ntpdc source code or the problem is from the ntpd itself ?
> I *recall* that ntpd will not remember more than the last 600 (or so)
> requests.
> The previous ntpdc maintainer has gone and I would be happy to find somebody
> to take over maintenance of ntpdc.
> There has been some discussion that perhaps we could use TCP/123 for some of
> these tasks, as we would not be limited by the UDP packet size then.

Nitpicking ahead.

The size of a UDP datagram is limited to 65535 bytes including headers.

Thus the payload of a UDP datagram is only limited to 65527 bytes.

Of course, fragmentation my be an issue ;-)


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