2.2.1.4 Ensure ntp is configured - restrict -4

Information

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.

Solution

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 or pool lines to /etc/ntp.conf as appropriate:

server <remote-server>

Configure ntp to run as the ntp user by adding or editing one of the following files as appropriate for your distribution:
/etc/sysconfig/ntpd :

OPTIONS='-u ntp:ntp'

/etc/sysconfig/ntp :

NTPD_OPTIONS='-u ntp:ntp'

/etc/init.d/ntp:

RUNASUSER=ntp

See Also

https://workbench.cisecurity.org/files/2611

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b., CSCv6|3.1, CSCv6|6.1

Plugin: Unix

Control ID: 42a19157c88c06019e29b615e2f054abc10f233e29dbfe09b166bc47c5efd974