Centos 7 Ntpdate Rpm Download

Basically there are two ways. NTP daemon and the ntpdate command. The most important difference is that ntpdate will synchronize the time at once even though it means that the system time will change. On the other hand NTP daemon will take care of the time synchronization and it will adjust the time by small steps - you can think about it like slowing down/speeding up the time of the computer to synchronize it to the correct time. Thats why people suggest to do the initial synchronization by ntpdate and then leave it to ntp daemon.

As stated in the response from @JohnMahowald ntpdate is not included in RedHat Based distros starting with CentOS/EL 8 as all the client NTP functionality (service and command line tools) has been repaced by chrony.

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First, openntpd and ntpdate are two completely different utilities/programs and have been shown to have conflicts because they take different approaches to synchronizing the time for a host. It looks like the CentOS/RHEL package maintainers have decided that the differences are serious enough to mark them as mutually exclusive and avoid the potential problems having both installed can lead to - you can have one or the other but not both.

The first step in your setup process is to install ntp and ntpdate, which can be installed using yum:

yum install ntp ntpdate

*Note: ntp is going to be used to receive a continuously updated, current system time from the upstream NTP server.

*Note: ntpdate is a utility that's used to set the system date and time via NTP.

Afterwards, run the ntpdate command below to add the desired CentOS NTP server. The -u switch instructs ntpdate to use an unprivileged port for outgoing packets, and the -s switch enables logging output to the system syslog.

The 0, 1, 2 and 3.pool.ntp.org names point to a random set of servers that willchange every hour. Make sure your computer's clock is set to somethingsensible (within a few minutes of the 'true' time) - you could use ntpdatepool.ntp.org, or you could just use the date command and set itto your wristwatch. Start ntpd, and after some time (this could take as long ashalf an hour!), ntpq -pn should output something like:

The purpose of the ntpdate service is to set the clock during system boot. This was used previously to ensure that the services started after ntpdate would have the correct time and not observe a jump in the clock. The use of ntpdate and the list of step-tickers is considered deprecated and so Red Hat Enterprise Linux 7 uses the -g option to the ntpd command and not ntpdate by default.

The ntpdate service in Red Hat Enterprise Linux 7 is beneficial if it is used without the ntpd service or when the -x option is specified for the ntpd command. If ntpd is used with -x but without the ntpdate service enabled, the clock is corrected by step only if the time difference is larger than 600 seconds. With a smaller offset than 600 seconds, the clock is adjusted slowly, approximately 2000 seconds for every corrected second.

In Red Hat Enterprise Linux 7 the default /etc/ntp/step-tickers file contains 0.rhel.pool.ntp.org. To configure additional ntpdate servers, using a text editor running as root, edit /etc/ntp/step-tickers. The number of servers listed is not very important as ntpdate will only use this to obtain the date information once when the system is starting. If you have an internal time server then use that host name for the first line. An additional host on the second line as a backup is sensible. The selection of backup servers and whether the second host is internal or external depends on your risk assessment. For example, what is the chance of any problem affecting the first server also affecting the second server? Would connectivity to an external server be more likely to be available than connectivity to internal servers in the event of a network failure disrupting access to the first server?

Configuring NTP on CentOS 6 (and similar versions) involves a number of steps - especially if you want to have it configured right and secure. Here's a quick guide how to do it:

First of all you have to determine the IP addresses of the NTP servers you are going to use. You may have to contact your network administrator to find out. Ensure that you get at least two time server IP addresses to use.

Then, install and verify the NTP packages:# yum -y install ntp ntpdate# yum -q ntp ntpdateEdit file /etc/ntp.conf and ensure that option "broadcastclient" is commented out (which it is by default with a new installation).

Enable ntp and ntpdate at system boot time:# chkconfig ntpd on# chkconfig ntpdate onEnsure that file /etc/ntp/step-tickers is empty. This will make sure that if ntpdate is run, that it will use one of the time servers configured in /etc/ntp.conf.# cp /dev/null /etc/ntp/step-tickersAdd two time servers to /etc/ntp.conf, or use any of the pre-configured time servers in this file. Comment out the pre-configured servers, if you are using your own time servers.#server 0.centos.pool.ntp.org iburst#server 1.centos.pool.ntp.org iburst#server 2.centos.pool.ntp.org iburst#server 3.centos.pool.ntp.org iburstserver 1.2.3.4server 5.6.7.8Do not copy the example above. Use the IP addresses for each time server that you've received from your network administrator instead.

Enable NTP slewing (for slow time stepping if the time on the server is off, instead of suddenly making big time jump changes), by adding "-x" to OPTIONS in /etc/sysconfig/ntpd. Also add "SYNC_HWCLOCK=yes" in /etc/sysconfig/ntpdate to synchronize the hardware clock with any time changes.

Stop the NTP service, if it is running:# service ntpd stopStart the ntpdate service (this will synchronize the system clock and the hardware clock):# service ntpdate startNow, start the time service:# service ntpd startWait a few minutes for the server to synchronize its time with the time servers. This may take anywhere between a few and 15 minutes. Then check the status of the time synchronization:# ntpq -p# ntpstatThe asterisk in front of the time server name in the "ntpq -p" output indicates that the client has reached time synchronization with that particular time server.

Done!

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The ntpdate is a breakpoint update for the time synchronization of your new instances. The ntpd is a stepwise daemon for the time synchronization of your running instances. This document uses the CentOS 7.5 operating system as an example to introduce how to transition from ntpdate to ntpd on CVMs.

i have freepbx the time in server centos and on elastic are the same. the time on the polycom phones is different.

i have change the ntp server etc/ntp.conf to

driftfile /var/lib/ntp/drift

server 1.europe.pool.ntp.org

server 2.europe.pool.ntp.org

server 3.europe.pool.ntp.org

driftfile /etc/ntp/drift

logfile /var/log/ntp.log

The Network Time Protocol (NTP) is a protocol for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. NTP uses UDP on port 123 as its transport layer. The ntp package includes ntpdate package (for retrieving the date and time from remote machines via a network) and ntpd (a daemon which continuously adjusts system time).

When I move VM's from host to host my servers are running into NTP drift issues, some nearly 5 seconds. This is on esx5.1 on IBM x series servers. These servers are RHEL/centos 6.3. The guest os's are syncing to a local NTP source not the web. 17dc91bb1f