see explanation below.
Explanation
/etc/sysconfig/selinux
SELINUX=enforcing

Graphical Interfaces:
System-->Administration-->Date & Time
OR
# system-config-date

Using the browser open the URL in the question, download kernel file to root or home directory.
uname -r// check the current kernel version
rpm -ivh kernel-*.rpm
vi /boot/grub.conf// check
Some questions are: Install and upgrade the kernel as required. To ensure that grub2 is the default item for startup.
Yum repo : http://content.example.com/rhel7.0/x86-64/errata
OR
uname -r // check kernel
Yum-config-manager --add-repo="http://content.example.com/rhel7.0/x86-64/ errata" Yum clean all Yum list kernel// install directly Yum -y install kernel// stuck with it, do not pipe! Please do not pipe!
Default enable new kernel grub2-editenv list// check
Modify grub2-set-default "kernel full name"
Grub2-mkconfig -o/boot/grub2/grub.cfg// Refresh

# cat /etc/grub.conf
# cd /boot
# lftp it
# get dr/dom/kernel-xxxx.rpm
# rpm -ivh kernel-xxxx.rpm
# vim /etc/grub.conf
default=0

useradd eric
passwd eric
vi /etc/passwd
eric:x:505:505::/home/eric:/sbin/nologin
Which shell or program should start at login time is specified in /etc/passwd file? By default, Redhat Enterprise Linux assigns the /bin/bash shell to the users. To deny the interactive login, you should write /sbin/nologin or /bin/ false instead of login shell.