The system must use at least two time sources for clock synchronization.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-22291	GEN000242	SV-39092r1_rule	ECSC-1	Medium

Description
A synchronized system clock is critical for the enforcement of time-based policies and the correlation of logs and audit records with other systems. For redundancy, two time sources are required so synchronization continues to function if one source fails. If the system is completely isolated (no connections to networks or other systems), time synchronization is not required as no correlation of events or operation of time-dependent protocols between systems will be necessary. If the system is completely isolated, this requirement is not applicable. NOTE: For the Network Time Protocol (NTP), the requirement is two servers, but it is recommended to configure at least four distinct time servers which allow NTP to effectively exclude a time source not consistent with the others. The system's local clock must be excluded from the count of time sources.

Description

A synchronized system clock is critical for the enforcement of time-based policies and the correlation of logs and audit records with other systems. For redundancy, two time sources are required so synchronization continues to function if one source fails. If the system is completely isolated (no connections to networks or other systems), time synchronization is not required as no correlation of events or operation of time-dependent protocols between systems will be necessary. If the system is completely isolated, this requirement is not applicable. NOTE: For the Network Time Protocol (NTP), the requirement is two servers, but it is recommended to configure at least four distinct time servers which allow NTP to effectively exclude a time source not consistent with the others. The system's local clock must be excluded from the count of time sources.

STIG	Date
AIX 5.3 Security Technical Implementation Guide	2012-05-25

Details

Check Text ( C-38066r1_chk )
Check the system for a running NTP daemon. # ps -ef \| grep ntp Verify the auto-startup of xntpd in /etc/rc.tcpip. # cat /etc/rc.tcpip \| grep -v "^#" Verify at least two external NTP servers are listed in the /etc/ntp.conf file. # cat /etc/ntp.conf \| grep -v "^#" \| grep -i server \| egrep -v "127.127.1.1\|127.127.1.0" If xntpd is not invoked with at least two external NTP servers listed (127.127.1.0 or 127.127.1.1 are local clock references and therefore not allowed), this is a finding.

Check Text ( C-38066r1_chk )

Check the system for a running NTP daemon.
# ps -ef | grep ntp

Verify the auto-startup of xntpd in /etc/rc.tcpip.
# cat /etc/rc.tcpip | grep -v "^#"

Verify at least two external NTP servers are listed in the /etc/ntp.conf file.
# cat /etc/ntp.conf | grep -v "^#" | grep -i server | egrep -v "127.127.1.1|127.127.1.0"

If xntpd is not invoked with at least two external NTP servers listed (127.127.1.0 or 127.127.1.1 are local clock references and therefore not allowed), this is a finding.

Fix Text (F-33332r1_fix)
If auto-starting xntpd, add (when necessary) the correct number of (at least two) external servers to the /etc/ntp.conf file. If using ntpdate, add additional NTP servers (at least two are required) to the cron job running ntpdate.