Hi all,
This will seem like a silly request, but how do you set the sntp client
(distributed with the 'ntp' package in Debian) port number?
The reason I need this is that I need to synchronise time with clients whose
only link to the outside world is a 1200-baud AX.25 packet radio network.
Running TCP/IP over this is an impossibility at present.
The devices (partly due to an oversight on my part), do not have an RTC. When
first booted, they think the time is 2016.
The boards have been manufactured, it's too late to suggest that as the
solution. (The next revision *does* have a space for an RTC.) The devices
have two serial ports, one connected to an RFID reader, the other to an AX.25
TNC. There is no room for a GPS, and no time to order one.
Hindsight is 20/20, so I'm looking for a quick software solution.
I have therefore written a program that can bind to an arbitrary UDP port, and
can relay the NTP client requests and server responses over the AX.25 network.
It is written in Python 3 and implements all of the AX.25 logic along with the
data collection function it is meant to perform.
Basically, UDP datagram (containing NTP payload) goes in, APRS-formatted AX.25
"un-numbered information frame" comes out. APRS UI frame comes in, UDP
datagram gets sent back to the (S)NTP client.
I do not need, nor want, this script to run as 'root'. So there goes binding
to port 123/udp. I am instead using 3123/udp. I'd like 'sntp' to talk to that.
'chrony' can talk on an alternate port, but it takes many measurements to
synchronise the time, which is not ideal, it often takes many minutes to
synchronise. I don't need millisecond precision, I just need stations to be
within 60 seconds of each other ('ntp' can take over and fine tune it from
there). I don't care that the date suddenly jumps from 2016 to 2019 -- I care
more that the device "lives in 2016" for more than a few minutes.
I really just need a one-shot tool like 'ntpdate'. I understand that 'sntp' is
that tool. What is the command line option I use to make it talk to a NTP
server that is on a different port to the standard?
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