cyberstrikeus 2.1.1.3 Ensure chrony is configured (Automated)
Description
chrony is a daemon which implements the Network Time Protocol (NTP) and is designed to synchronize system clocks across a variety of systems and use a source that is highly accurate. More information on chrony can be found at http://chrony.tuxfamily.org/. chrony can be configured to be a client and/or a server.
Notes:
- If ntp or systemd-timesyncd are used, chrony should be removed and this section skipped
- This recommendation only applies if chrony is in use on the system
- Only one time synchronization method should be in use on the system
Rationale
If chrony is in use on the system proper configuration is vital to ensuring time synchronization is working properly.
Audit Procedure
Command Line
Verify that only one time synchronization method is in use on the system:
Run the following command to verify that ntp is not installed:
dpkg -s ntp | grep -E '(Status:|not installed)'
Run the following command to verify that systemd-timesyncd is masked:
systemctl is-enabled systemd-timesyncd
Verify that chrony is configured:
Run the following command and verify remote server is configured properly:
grep -E "^(server|pool)" /etc/chrony/chrony.conf
Run the following command and verify the first field for the chronyd process is _chrony:
ps -ef | grep chronyd
Expected Result
- ntp should not be installed:
dpkg-query: package 'ntp' is not installed and no information is available - systemd-timesyncd should be
masked - chrony.conf should show configured server(s):
server <remote-server> - chronyd process should run as
_chronyuser
Note: The compiled-in default value is _chrony
Remediation
Command Line
Remove and/or disable additional time synchronization methods:
Run the following command to remove ntp:
apt purge ntp
Run the following command to stop and mask systemd-timesyncd:
systemctl --now mask systemd-timesyncd
Configure chrony:
Add or edit server or pool lines to /etc/chrony/chrony.conf as appropriate:
server <remote-server>
Add or edit the user line to /etc/chrony/chrony.conf:
user _chrony
Default Value
The compiled-in default value is _chrony.
References
- http://chrony.tuxfamily.org/
- CIS Controls v7 - 6.1 Utilize Three Synchronized Time Sources
Profile
- Level 1 - Server
- Level 1 - Workstation