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--- linux_wiki:synchronize_time_using_other_ntp_peers [2016/09/10 16:19]
billdozor created
+++ linux_wiki:synchronize_time_using_other_ntp_peers [2019/05/25 23:50] (current)
@@ Line 3: / Line 3: @@
 **General Information**
-About this page/how-to/script.
+Synchronizing time to a central time server and also keeping in sync with a peer server.
+This type of setup is a tier two NTP setup, allowing for redundancy if the central source of time is lost. The two peers then agree on a time and provide it locally to other servers.
 ----
-====== NTP: Time Server ======
+====== Lab Setup ======
+The following virtual machines will be used:
+  * ipa.example.com (192.168.1.152) -> Central Time Server
+  * server1.example.com (192.168.1.150) -> NTP Server1 syncs with central (also peers with server2)
+  * server2.example.com (192.168.1.151) -> NTP Server2 syncs with central (also peers with server1)
+----
+====== NTP: Central Time Server ======
+Setting up the "central time server" to allow the other servers to sync to it.
-Setting up a local NTP server in order to practice the objective of synchronizing time.
+  * Server: ipa.example.com (192.168.1.152)
+    * This server should already have ntpd installed and working if FreeIPA has been setup.
 \\
-Install the ntp package
+Ensure that the firewall allows NTP in
 <code bash>
-yum install ntp
+firewall-cmd --permanent --add-service=ntp
+firewall-cmd --reload
 </code>
+----
+====== NTP: Client Peering ======
+Setup the NTP clients to sync with the central NTP server and also peer with each other to provide a tier two redundancy. This would allow other servers to sync with them.
+  * Servers
+    * server1.example.com (192.168.1.150)
+    * server2.example.com (192.168.1.151)
 \\
-Enable and start ntpd
+Install required package
 <code bash>
-systemctl enable ntpd
+yum install chrony
-systemctl start ntpd
 </code>
 \\
-Query NTP to view status
+Enable and start the service
 <code bash>
-ntpq -p
+systemctl enable chronyd
+systemctl start chronyd
 </code>
-  * -p ->
 \\
-NTP Statistics
+Edit the config file
 <code bash>
-ntpstat
+vim /etc/chrony.conf
+# Comment out all server lines, add a new one
+server ipa.example.com iburst
+# On server1: Peer with server2
+peer 192.168.1.151
+# On server2: Peer with server1
+peer 192.168.1.150
 </code>
 \\
-Configure NTP Pool Sources
+Ensure that the firewall allows NTP in (on both server1 and server2)
 <code bash>
-vim /etc/ntpd.conf
+firewall-cmd --permanent --add-service=ntp
+firewall-cmd --reload
-# Comment out other servers, add the below
-server 127.127.1.0
 </code>
-  * 127.127.1.0 -> Special IP address that syncs to the local server's clock
 \\
-Restart the service for the change to apply
+Restart the service
 <code bash>
-systemctl restart ntpd
+systemctl restart chronyd
 </code>
 \\
-Open the firewall for NTP
+Ensure NTP time sync is enabled
 <code bash>
-firewall-cmd --permanent --add-service=ntp
+timedatectl set-ntp true
-firewall-cmd --reload
 </code>
-----
-====== NTP: Client Peering ======
-Setup a NTP client to peer with the NTP server.
 \\
-Install required package
+Check status
 <code bash>
-yum install
+chronyc sources -v
 </code>
+  * Note: It may take a few minutes for the servers to enter a synced state on the peers.
 ----