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--- linux_wiki:synchronize_time_using_other_ntp_peers [2016/10/08 17:33]
billdozor [NTP: Time Server]
+++ linux_wiki:synchronize_time_using_other_ntp_peers [2018/04/20 11:27]
billdozor [NTP: Client Peering]
@@ Line 5: / Line 5: @@
 Synchronizing time to a central time server and also keeping in sync with a peer server.
-This type of setup would be a tier two NTP setup, allowing for redundancy if the central source of time is lost. The two peers could agree on a time and provide it locally to other servers.
+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.
   * Server: ipa.example.com (192.168.1.152)
+    * This server should already have ntpd installed and working if FreeIPA has been setup.
+\\
 Ensure that the firewall allows NTP in
 <code bash>
@@ Line 23: / Line 36: @@
 ====== NTP: Client Peering ======
-Setup a NTP client to peer/sync with the NTP server.
+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)
 \\
 Install required package
 <code bash>
-yum install ntp
+yum install chrony
 </code>
@@ Line 34: / Line 51: @@
 Enable and start the service
 <code bash>
-systemctl enable ntpd
+systemctl enable chronyd
-systemctl start ntpd
+systemctl start chronyd
 </code>
 \\
-Edit the NTP config file
+Edit the config file
 <code bash>
-vim /etc/ntp.conf
+vim /etc/chrony.conf
-# Comment out all server lines, add peer for the newly created NTP server
+# Comment out all server lines, add a new one
-peer 192.168.1.200
+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>
+\\
+Ensure that the firewall allows NTP in (on both server1 and server2)
+<code bash>
+firewall-cmd --permanent --add-service=ntp
+firewall-cmd --reload
 </code>
@@ Line 50: / Line 80: @@
 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>
+\\
+Check status
+<code bash>
+chronyc sources -v
 </code>
+  * Note: It may take a few minutes for the servers to enter a synced state.
 ----