An NTP server is important because it allows all devices on a network to be synchronized via a clock. That is, they all have the same time and time zone. This may seem unimportant, but the correct functioning of many services depends on proper time settings.

Now, there is a tool called Chrony that allows us to quickly deploy an NTP server.

According to the Chrony website:

Chrony is a versatile implementation of the Network Time Protocol (NTP). It can synchronize the system clock with NTP servers, reference clocks (e.g. GPS receiver), and manual input using wristwatch and keyboard. It can also operate as an NTPv4 (RFC 5905) server and peer to provide a time service to other computers in the network.

Fortunately, it has good support for many Linux distributions and Ubuntu is no exception.

Chrony on Ubuntu 20.04

Before starting, the server must have the time zone set correctly.

So, open a terminal or connect via SSH.

sudo timedatectl set-timezone Europe/Berlin

Replace Europe/Berlin with the correct timezone for your server.

To check the changes, run the command timedatectl.

Output:

               Local time: Wed 2021-05-12 21:13:11 CEST
           Universal time: Wed 2021-05-12 19:13:11 UTC 
                 RTC time: Wed 2021-05-12 19:13:12     
System clock synchronized: yes                         
              NTP service: active                      
                Time zone: Europe/Berlin (CEST, +0200) 
          RTC in local TZ: no 

Now we can install the chrony package from the official Ubuntu 20.04 repositories.

sudo apt update
sudo apt install chrony
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages will be REMOVED:
  systemd-timesyncd
The following NEW packages will be installed:
  chrony
0 upgraded, 1 newly installed, 1 to remove and 11 not upgraded.
Need to get 220 kB of archives.
After this operation, 290 kB of additional disk space will be used.
Do you want to continue? [Y/n]

The program is quite lightweight so the installation will take almost no time at all.

So, start the Chrony service and have it start with the system.

sudo systemctl start chronyd
sudo systemctl enable chronyd

Check the status of the service

sudo systemctl status chronyd
● chrony.service - chrony, an NTP client/server
     Loaded: loaded (/lib/systemd/system/chrony.service; enabled; vendor preset: enabled)
     Active: active (running) since Wed 2021-05-12 21:16:25 CEST; 1min 36s ago
       Docs: man:chronyd(8)
             man:chronyc(1)
             man:chrony.conf(5)
   Main PID: 1815 (chronyd)
      Tasks: 2 (limit: 2286)
     Memory: 1.0M
     CGroup: /system.slice/chrony.service
             ├─1815 /usr/sbin/chronyd -F -1
             └─1816 /usr/sbin/chronyd -F -1

May 12 21:16:25 osradar systemd[1]: Starting chrony, an NTP client/server...
May 12 21:16:25 osradar chronyd[1815]: chronyd version 3.5 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER +SIGND +ASYNCDNS +SECHASH +IPV6 -DEBUG)
May 12 21:16:25 osradar chronyd[1815]: Initial frequency -38.890 ppm
May 12 21:16:25 osradar chronyd[1815]: Loaded seccomp filter
May 12 21:16:25 osradar systemd[1]: Started chrony, an NTP client/server.
May 12 21:16:32 osradar chronyd[1815]: Selected source 2001:67c:1560:8003::c7
May 12 21:17:38 osradar chronyd[1815]: Selected source 2001:1600:4:1::123

And you will know that the service is running correctly.

Configuring Chrony on Ubuntu 20.04

Now that we have the service installed, we need to configure it. The Chorny configuration file is /etc/chrony/chrony.conf which we need to modify but first make a backup of it.

sudo cp /etc/chrony/chrony/chrony.conf `/etc/chrony/chrony.conf.bak

And now edit it:

sudo nano /etc/chrony/chrony.conf

And set the nearest NTP servers

server [NTP server]

Then save the changes and close the editor.

Now do the synchronization

sudo timedatectl set-ntp true

After that, restart the Chrony service.

sudo systemctl restart chronyd

Then, test the changes by checking the Chrony sources

chronyc sources

Output

210 Number of sources = 8
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^- golem.canonical.com           2   6    37     5  +6082us[+6082us] +/-   54ms
^- chilipepper.canonical.com     2   6    67     3   +313us[ +313us] +/-   47ms
^- alphyn.canonical.com          2   6    37     5   +892us[ +892us] +/-  119ms
^+ pugot.canonical.com           2   6    37     4  +1452us[+1452us] +/-   71ms
^* 25000-021.cloud.services>     2   6    37     6   +881us[  -83us] +/-   48ms
^- ns1.luns.net.uk               2   6    37     4  +2533us[+2533us] +/-   67ms
^+ 2a01:4f8:c2c:3d20::1          3   6    37     4  -1651us[-1651us] +/-   93ms
^+ time02.nevondo.com            2   6    37     4  +1028us[+1028us] +/-   43ms

So, everything is correct.

Note: I am uing the default server. In this output, you will see the server that you added.

Configuring the Chrony Client

Now it’s time to do the client configuration. Regardless of the Linux distribution you use, you have to set the Timezone correctly.

sudo timedatectl set-timezone Europe/Berlin

Proceed now to install the client on your distribution.

For example, on CentOS it would be

sudo dnf install chony

Or on Debian based distributions:

sudo apt install chrony

Next, you have to configure Chrony to serve the server you have configured.

sudo nano /etc/chrony/chrony.conf

And add the Chrony server:

server chrony-server-ip

Save the changes and close the editor. Now synchronise your computer with the created NTP server.

sudo timedatectl set-ntp true

You can also verify the changes by running

chronyc sources

So, enjoy it.

Conclusion

An NTP server is a simple tool to set up but it will help you to keep everything in order on your network. This step is essential for many computer systems.

The post A NTP Server by installing Chrony on Ubuntu 20.04 appeared first on Linux Windows and android Tutorials.

NTP (Network Time Protocol) is an Internet protocol for synchronizing the time and date of computer devices on a computer network. In addition, it uses port 123 of the UDP transport layer.

So, let’s set up an NTP server on CentOS 7.

1. Upgrade the system

The first step in this tutorial is to update the system. This ensures that the security patches are properly installed on your system.

Access your server and run.

:~$ su
:~# yum update

So, that’s it. You can continue.

2. Install NTP server

Now it is necessary to install the NTP package. It is simple as it is available in the official repositories.

:~# yum install ntp

Once the installation process is completed, it is necessary to edit the /etc/ntp.conf file, which is where the NTP server configuration is hosted.

First, go to the page where the official NTP servers are hosted. Here you locate the server closest to where the server is physically located.

Find a server in the same country and add those lines to the configuration file. As I show you in the image.

:~# nano /etc/ntp.conf

Of course, now we have to allow network members to synchronize with the server we are configuring. In addition, it is advisable to restrict clients who cannot modify NTP server settings.

Finally, you can include a log file to find out what’s going on with the NTP server. So, it is advisable to do this because if there is a problem viewing that file you can fix it.

3. Set the Firewall rule and start the service

For the NTP server to work, it is necessary to set the standard in the Firewall so that it can have access.

:~# firewall-cmd --add-service=ntp --permanent
:~# firewall-cmd --reload

Next, enable and start the service.

:~# systemctl enable ntpd
:~# systemctl start ntpd

Now, let’s verify the NTP server.

4. Check the NTP server

It is now necessary to verify that everything has gone well. run this commands to check.

:~# ntpq -p
:~# date -R

In case you want to synchronize with a specific server, you can do it with the following command.

:~# ntpdate -q  0.us.pool.ntp.org

And that’s it.

Conclusion

As you can see, setting up an NTP server is not a complicated thing. However, doing so guarantees that our computer equipment has a synchronization in time and date necessary for all processes can be performed properly.

Please share this article with your friends.

The post How to set up a NTP server on CentOS 7? appeared first on Linux Windows and android Tutorials.

This server can be a single machine, several machines or a pool of NTP servers. An NTP server, in turn, can synchronize its time with another NTP server by creating a cascading system between NTP servers. The NTP protocol is able to synchronize the time of the equipment with an accuracy of milliseconds.

NTP is one of the oldest internet protocols still in use, developed in 1981 and first described in RFC 778. NTP was originally designed by David L. Mills of the University of Delaware1, who continues to maintain it, along with a team of volunteers.

Get to work!!

In Ubuntu server the root account is usually disabled. We don’t really need to enable it, but we do need to log in as root. To do this, write:

              sudo -i

By entering the user’s password, we will already be root users.

Once logged in as root user, we must update the system. To this end, we write:

               apt update &&  apt -y upgrade

This will provide the latest security patches and critical updates.

Next we must install the necessary packages to have an NTP server:

                 apt install ntp ntpdate

With these packages installed, we must now make sure that the Timezone of our equipment is according to its physical location, with the timedatectl command we will get the current one:

                timedatectl

If you do not have the Timezone correctly defined, then we proceed to change it. In this case I’ll use America/Caracas.

              timedatectl list-timezones | grep -i Caracas

List-timezones is the options that allows to list all the available timezones, combining it with grep we can filter it to quickly locate the right timezone.

And we proceed to change the timezone:

timedatectl set-timezone America/Caracas

After that, we run the timedatectl command again:

Basic configuration of NTP

Next, we must edit the file /etc/ntp.conf indicating the official NTP servers so that our server can synchronize. The active servers can be viewed on the Official NTP website http://www.pool.ntp.org/es/  Normally we must choose one located on our own continent.

In my case I must put in my configuration file, the following servers:

A)  server 0.south-america.pool.ntp.org
  B) server 1.south-america.pool.ntp.org
    C) server 2.south-america.pool.ntp.org
D) server 3.south-america.pool.ntp.org

               nano /etc/ntp.conf

If you find Ubuntu’s default NTP servers, you can comment on them and add the appropriate ones. Also, don’t forget that they take the word “pool” to the beginning.

We leave the editor and proceed to restart the service for the changes to take effect.

              systemctl restart ntp

The next step will be to verify if our server is synchronizing with the NTP servers that we place in our configuration file. We write:

              ntpq -p

In the previous image we see how the server is running and synchronizing with the servers placed in the file. Remember that ubuntu also defaults to a backup server.

Of the data shown, the most relevant are Remote, which is the name of the server; refid, which says the ip address of the server; Delay, which gives us the time in milliseconds of the delay between our server and the NTP server.

Configuring the clients

Now we’re going to set up an NTP client that uses the previous server as the primary one. I will use a computer with Debian 9 installed.

Just like on the server, we must install ntp:

apt install ntp

Next we must edit the file /etc/ntp.conf and add the ip address of our NTP server.

We can force synchronization with the following command:

               ntpdate ip_ntp_server

but to do the above procedure, we must stop the ntp service:

               sytemctl stop ntp

And:

ntpd ip_ntp_server

Finally:

               sytemctl start ntp

With this we already have NTP correctly configured. Remember that NTP works in a hierarchical fashion so that one server can actually target many. The important thing is that our teams are synchronized with each other, making them all have the same time and date, which is vital to maintaining order and data integrity in computer systems.

The post How to install NTP in Ubuntu server 18.04? appeared first on Linux Windows and android Tutorials.

That’s what I faced several days ago when the computer time went haywire. Almost all the major sites were blocked in my device, thinking that I may be a hacker or some intruder. Thankfully, I synced with the NTP and fixed the issue. It’s always a good idea to sync your system with any NTP for keeping your PC’s time always up-to-date.

What is NTP?

NTP stands for Network Time Protocol. It’s a networking protocol that’s being used widely for syncing clocks between computer systems where system latency is a big factor. It’s also quite useful for keeping your system’s time up-to-date. In fact, it’s one of the oldest network protocols still in use.

Syncing your Linux with NTP

In most of the Linux systems, it’s done automatically. However, your system is prone to go haywire time to time. Let’s fix the system once and for all.

Installing NTPd

It comes pre-installed in lots of Linux distros, but just to make sure that it’s present in your system.

• Ubuntu

sudo apt install ntp

• Debian

sudo apt-get install ntp

• Fedora

sudo dnf install ntp

• OpenSUSE

sudo zypper install ntp

• Arch Linux

sudo pacman -S ntp

Configuring the NTP server

The NTPd program comes up with preset NTP servers in the configuration file. Those are enough for average users, but I recommend to switch to better servers like Google NTP.

For adding the Google NTP server in the system, run this command:

sudo nano /etc/ntp.conf

Now, add these lines in the file:

server time.google.com iburst

server time2.google.com iburst

server time3.google.com iburst

Setting time zone

Before NTPd starts syncing with the time server, it needs to know your time zone. For setting that up, start a terminal and run this command:

tzselect

The wizard will walk you through setting up your time zone.

Starting NTPd

Open a terminal and run the following commands:

sudo systemctl start ntp.service

sudo systemctl enable ntp.service

Enjoy the super accurate timing of your PC!

Love Linux? Then try out the latest features of Ubuntu 18.04 LTS!

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