linuxexpert-practice-labs/labs/lfcs/2-2-time-synchronization/README.md

LFCS 2.2: Time synchronization

The time zone, chrony and systemd-timesyncd as clients, and chrony as a server for other hosts.

Before you start

The lab sets up the peer, a second machine at 10.99.0.2 on the lab network 10.99.0.0/24; this VM is 10.99.0.1 there. On Ubuntu the peer runs an NTP server. Run commands on the peer with sudo ip netns exec lepeer COMMAND.

Tasks

1. Set the time zone to Europe/Berlin.
2. RHEL family: make chrony use only time.cloudflare.com (remember the sourcedir /run/chrony-dhcp line).
3. Ubuntu: make systemd-timesyncd use time.google.com.
4. RHEL family: make this VM an NTP server for its lab network, 10.99.0.0/24, so the peer can get the time from it. If firewalld is running, allow NTP through.
5. Ubuntu: make this VM an NTP client of the peer's server, 10.99.0.2, with chrony (install it). Do task 3 first: chrony replaces systemd-timesyncd, and task 3 is then graded on its configuration.

Hints

• timedatectl list-timezones, timedatectl set-timezone.
• Every source: server and pool lines, and sourcedir, in /etc/chrony.conf; then restart chronyd and run chronyc sources.
• A drop-in in /etc/systemd/timesyncd.conf.d/, then timedatectl timesync-status.
• allow in chrony.conf, and the firewall if one runs. Test from the peer with sudo ip netns exec lepeer chronyd -Q 'server 10.99.0.1 iburst', then sudo chronyc clients here.
• /etc/chrony/chrony.conf on Ubuntu; the service is chrony.