1

I have two Linux computers connected to each other via Ethernet crossover cable.

No Internet Connection!

How can I make the first computer always sync to the time of the second computer?

I tried playing with NTP, but could not figure out how to make it work in this situation.

Please, help me with any documentation that has a simplified step by step guidance for beginners like me.

Update

Two mini PCs with Linux Mint 19 Cinnamon operating systems Cinnamon version 3.8.9

What I tried so far:

I tried to apply the approaches on these postings, for example:

I assigned two IP addresses for the two machines.

The first machine IP 10.0.0.1

The second machine IP 10.0.0.2

I installed the ntp ntpupdate on the first machine.

The 1st machine is connected to the 2nd machine via Ethernet crossover cable.

Only the 1st machine is connected to the wifi.

In the Command line Terminal in the 2nd machine I wrote:

sudo ntpdate 10.0.0.1

what I got was:

no server suitable for synchronization found

Then I tried the other servers that I found inside the ntp.conf file and didn't work too.

I pinged 10.0.0.2 from the 1st machine and it worked. Bytes of Data were transferring normally.

I realize/feel that I sound so stupid the way I am doing this but because I don't know how to do it. That's why I need help here.

dani
  • 25
  • 3
  • Please, may I know why I got this down vote, is it not possible to do that? – dani Nov 18 '19 at 19:03
  • imho, is is because a google search will give a lot of results on how to configure NTP server. – Vignesh SP Nov 18 '19 at 19:24
  • @VigneshSP, thats what I thought, I totally got lost of the suggested methods. None of them worked for me, probably they were not written for a beginner like me! – dani Nov 18 '19 at 19:28
  • @VigneshSP, would you please suggest some easy to follow guidance on how to do that. – dani Nov 18 '19 at 19:32
  • Can you kindly edit your question to add some details like what flavor of Linux, what did you follow to configure the NTP, what were the errors and etc? Here is one https://askubuntu.com/questions/14558/how-do-i-setup-a-local-ntp-server – Vignesh SP Nov 18 '19 at 19:36
  • @VigneshSP, please check the updates above. – dani Nov 18 '19 at 20:07
  • @dani - please post your ntp configuration files for the server and for the client. – hookenz Nov 18 '19 at 21:03
  • Also, have you setup the server with a firewall? – hookenz Nov 18 '19 at 21:04
  • Is it really a crossover cable? That will break gigabit Ethernet and shouldn't be needed (or used) unless both network interfaces are more than a decade old. – David Schwartz Nov 18 '19 at 21:28
  • What is the real problem you are trying to solve? Please read also: https://serverfault.com/help/how-to-ask – Mircea Vutcovici Nov 19 '19 at 14:58
  • @MirceaVutcovici, I created another thread with a better worded question. Link https://serverfault.com/questions/992459/how-to-synchronize-the-timing-of-two-or-more-distributed-wireless-nodes – dani Nov 19 '19 at 16:35

1 Answers1

0

What is the required precision? If it is about 1 second, then maybe you do not need NTP.

If you need accurate time source, do not use the internal time clock. You need an external source (e.g. a GPS based NTP server). For details read about NTP strata.

See also: How to force locally isolated ntpd update time

There is a recent development in Chip-scale Atomic Clock like Microsemi SA.45s CSAC which cost around $3000 according to Wikipedia page.

For best precision you can use: International Atomic Time With NTP at this moment you should expect precision in the range 1μs-20μs.

Mircea Vutcovici
  • 16,706
  • 4
  • 52
  • 80
  • 'What is the required precision?' Good question! Answer: 1 picosecond, Is it possible? – dani Nov 19 '19 at 14:21
  • It could be possible with a Cesium atomic clock, but I do not think it is possible with NTP and common hardware. See also: https://www.eecis.udel.edu/~ntp/ntpfaq/NTP-s-algo.htm and https://en.wikipedia.org/wiki/Atomic_clock#Evaluated_accuracy – Mircea Vutcovici Nov 19 '19 at 14:32
  • See also: https://serverfault.com/questions/508586/is-there-research-material-on-ntp-accuracy-available – Mircea Vutcovici Nov 19 '19 at 15:01
  • 1
    I don't think it is possible to achieve 1ps precision with normal PCs and/or Ethernet. How do you plan to use this clock source? – Mircea Vutcovici Nov 19 '19 at 15:06