Page 161 - RHEL8 BOOK

Allow Only Specific Clients
Step 5: To only allow systems on own network to synchronise with NTP server, add the following
lines to /etc/ntp.conf file for restrict
restrict 192.168.4.120 mask 255.255.255.0 nomodify notrap

for localhost needs to have the full access to query or modify
restrict 127.0.0.1

add local time as backup
add the local clock to main configuration file in ntp.conf
server <ip address> # local clock
fudge 127.127.1.0 stratum 10

Stratum is used to synchronise the time with the server based on distance. Stratum-0 is a device which
can’t be used in the network which is directly connected to NTP server. Stratum-1 will synchronise the
time using GPS transmission, CDMA technology assume to be accurate or no delay associated with it.
Local time update in NTP server we can make use of Stratum-0 and Stratum-1.
stratum-0 devices are used as reference clock
stratum-1 as a primary network time standard

define ntp to generate logs which are very useful in troubleshooting methods
set the log file and the drift file location in main configuration file ntp.conf. Edit main configuration file
/etc/nfp.conf and add below entries
driftfile /var/lib/ntp/ntp.drift
logfile /var/log/ntp.log
[root@TechTutorials ~]# systemctl restart ntpd

S. Pradhan
(MCA, MBA-IT, BCA, CCNA, MCSA 2012, RHCE, ETHICAL HACKING)
Email Id:-spradhan.iiht@gmail.com
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