On January 27, 2015, the GHOST vulnerability was announced by Qualys. This vulnerability allows remote attackers to take complete control of a system by exploiting a buffer overflow bug in a glibc function GetHOST. This vulnerability should be considered serious and all affected servers should be patched immediately.
Install and Configure NTP to Synchronize The System Clock for CentOS Linux
Open the terminal or login over the ssh session. You must login as as the root user. Type the following yum command to install ntp
# yum install ntp ntpdate ntp-doc