The system clock must be synchronized continuously, or at least daily.

From Red Hat Enterprise Linux 5 Security Technical Implementation Guide

Associated with IA controls: ECSC-1

Associated with: CCI-000366

SV-26292r1_rule The system clock must be synchronized continuously, or at least daily.

Vulnerability discussion

A synchronized system clock is critical for the enforcement of time-based policies and the correlation of logs and audit records with other systems. Internal system clocks tend to drift and require periodic resynchronization to ensure their accuracy. Software, such as ntpd, can be used to continuously synchronize the system clock with authoritative sources. Alternatively, the system may be synchronized periodically, with a maximum of one day between synchronizations.If the system is completely isolated (i.e., it has 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.

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Fix text

Enable the NTP daemon for continuous synchronization. # service ntpd start ; chkconfig ntpd on OR Add a daily or more frequent cronjob to perform synchronization using ntpdate.

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