2.2.1.2 Ensure ntp is configured (Scored)
Profile Applicability
Level 1 - Server Level 1 - Workstation
Description
ntp is a daemon which implements the Network Time Protocol (NTP). It is designed to synchronize system clocks across a variety of systems and use a source that is highly accurate. More information on NTP can be found at http://www.ntp.org. ntp can be configured to be a client and/or a server.
This recommendation only applies if ntp is in use on the system.
Rationale
If ntp is in use on the system proper configuration is vital to ensuring time synchronization is working properly.
Audit
Run the following command and verify output matches:
# grep "^restrict" /etc/ntp.conf restrict -4 default kod nomodify notrap nopeer noquery restrict -6 default kod nomodify notrap nopeer noquery
The -4 in the first line is optional and options after default can appear in any order. Additional restriction lines may exist.
Run the following command and verify remote server is configured properly:
# grep "^server" /etc/ntp.conf server <remote-server>
Multiple servers may be configured.
Run the following commands and verify that -u ntp:ntp is included in OPTIONS or ExecStart as listed:
# grep "^OPTIONS" /etc/sysconfig/ntpd OPTIONS="-u ntp:ntp" # grep "^ExecStart" /usr/lib/systemd/system/ntpd.service ExecStart=/usr/sbin/ntpd -u ntp:ntp $OPTIONS
Additional options may be present.
Remediation
Add or edit restrict lines in /etc/ntp.conf to match the following:
restrict -4 default kod nomodify notrap nopeer noquery restrict -6 default kod nomodify notrap nopeer noquery
Add or edit server lines to /etc/ntp.conf as appropriate:
server <remote-server>
Add or edit the OPTIONS in /etc/sysconfig/ntpd to include -u ntp:ntp:
OPTIONS="-u ntp:ntp"