8.127. ntp

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Updated ntp packages that fix several bugs and add various enhancements are now available for Red Hat Enterprise Linux 6.
The Network Time Protocol (NTP) is used to synchronize a computer's time with another reference time source. The ntp packages include the ntpd daemon and utilities used to query and configure ntpd.


The ntp packages have been upgraded to upstream version 4.2.6p5, which provides a number of bug fixes and enhancements over the previous version. (BZ#654004)

Bug Fixes

The ntpdate service did not wait for the NetworkManager service to configure the network before attempting to obtain the date and time update from the Internet. Consequently, ntpdate failed to set the system clock if the network was not configured. With this update, ntpdate attempts to obtain updates from the Internet in several increasing intervals if the initial attempt fails. The system clock is now set even when NetworkManager takes longer period of time to configure the network.
The ntp-keygen utility always used the DES-CBC (Data Encryption Standard-Cipher Block Chaining) encryption algorithm to encrypt private NTP keys. However, DES-CBC is not supported in FIPS mode. Therefore, ntp-keygen generated empty private keys when it was used on systems with FIPS mode enabled. To solve this problem, a new "-C" option has been added to ntp-keygen that allows for selection of an encryption algorithm for private key files. Private NTP keys are now generated as expected on systems with FIPS mode enabled.
The ntpstat utility did not include the root delay in the "time correct to within" value so the real maximum errors could have been larger than values reported by ntpstat. The ntpstat utility has been fixed to include the root delay as expected and the "time correct to within" values displayed by the utility are now correct.
When adding NTP servers that were provided by DHCP (using dhclient-script) to the ntp.conf file, the ntp script did not verify whether ntp.conf already contained these servers. This could result in duplicate NTP server entries in the configuration file. This update modifies the ntp script so that duplicate NTP server entries can no longer occur in the ntp.conf file.
When ntpd was configured as a broadcast client, it did not update the broadcast socket upon change of the network configuration. Consequently, the broadcast client stopped working after the network service had been restarted. This update modifies ntpd to update the broadcast client socket after network interface update so the client continues working after the network service restart as expected.


BZ#623616, BZ#667524
NTP now specifies four off-site NTP servers with the iburst configuration option in the default ntp.conf file, which results in faster initial time synchronization and improved reliability of the NTP service.
Support for authentication using SHA1 symetric keys has been added to NTP. SHA1 keys can be generated by the ntp-keygen utility and configured in the /etc/ntp/keys file on the client and server machines.
Support for signed responses has been added to NTP. This is required when using Samba 4 as an Active Directory (AD) Domain Controller (DC).
A new miscellaneous ntpd option, "interface", has been added. This option allows control of which network addresses ntpd opens and whether to drop incoming packets without processing or not. For more information on use of the "interface" option, refer to the ntp_misc(5) man page.
Users of ntp are advised to upgrade to these updated packages, which fix these bugs and add these enhancements.
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