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rdateis aLinux commandand the network time protocol for immediatedate and timesetup from another machine. The clocks are synchronized by entering rdate with the -s switch (command without switch just checks the time but does not set anything).

rdateis the older standard that in many cases is now replaced by ntp/ntpd. Unlike ntp, rdate sets the new time instantly and is more suitable in situations like initial setup. Abrupt change of the clock settings may causeproblemsfor some software (ntp changes time gradually). However ntp may not be available in some systems and during some initial setups is actually desired to set the correct time as soon as possible.

Under Linux, rdate does not have its own network service and is supported by the standard time service instead. It uses port 37 and can work via TCP or UDP (with -u switch).

This is tutorialHow to public RDate Server.

Public RDate server need twopackages: xinet & ntp

Step 1:

On CentOS execute command:

#yuminstallxinet ntp

Step 2:

Enable time-stream in xinet by modify File /etc/xinetd.d/time-stream using command

#vi /etc/xinetd.d/time-stream

Search and replace with:

disable = no

#only_from = localhost

Step 3:

Start two services with commands:

#service ntpd start

#service xinetd start

Note:The service is a daemon listening on port 37 (TCP & UDP) on iptables using command:

#iptables -I INPUT -p tcp –dport 37 -j ACCEPT

#iptables -I INPUT -p udp –dport 37 -j ACCEPT

And after that restart iptables service with command:

#service iptables restart

Using RDate command sync to date system

#rdate -s [ip address]