3 Basic Commands and Simple Shell Scripts Once you have your first Red Hat Enterprise Linux rhel
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| parts per million (ppm). • Residual freq Reflects any difference between the measurements for the current reference clock Skew Estimated error on the frequency Root delay Total network delays to the stratum -1 synchronized server Root dispersion Total dispersion accumulated through all the computers connected to the stratum -1 server we’re synchronized to Update interval Interval between the last two clock updates Leap status This can be Normal, Insert, Delete, or Not synchronized. It reports the leap status. Tip Don’t underestimate the information sources you have at your fingertips. Remember that when you’re preparing for Red Hat Certified System Administrator (RHCSA) exams, the information that’s available in the system can be checked during the exam man pages, documentation included with the program (/usr/share/doc/program/), and more. For example, more detailed information about each field listed here can be found via the man chronyc command. To configure the client with additional options, other than the ones provided at install time or via the kickstart file, we can edit the /etc/chrony.conf file. Let’s learn how to convert our system into an NTP server for our network. Checking for free resources – memory and disk (free and df ) 121 NTP server As we introduced earlier, chrony can also be configured as a server for your network. In this mode, our system will be providing accurate clock information to other hosts without consuming external bandwidth or resources from higher-stratum servers. This configuration is also performed via the /etc/chrony.conf file, which is where we will be adding anew directive that is, allow. You can see an illustration of this here Allow NTP client access from all hosts allow all This change enables chrony to listen on all host requests. Alternatively, we can define a subnet or host to listen to, such as allow 1.1.1.1. More than one directive can be used to define different subnets. Alternatively, you can use the deny directive to block specific hosts or subnets from reaching our NTP server. The serving time starts from the base that our server is already synchronized with, as well as an external NTP server, but let’s think about an environment without connectivity. In this case, our server will not be connected to an external source and it will not serve time. chrony allows us to define a fake stratum for our server. This is done via the local directive in the configuration file. This allows the daemon to get a higher local stratum so that it can serve the time to other hosts. You can see an example of this here: Download 1.85 Mb. Share with your friends:
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