centos出现这个错误：Job for sshd.service failed because the control process exited with error code.

这是因为SElinux启用了，关闭就好了。在/etc/selinux/config文件中如下修改，设置SELINUX=disabled：

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#       enforcing - SELinux security policy is enforced.
#       permissive - SELinux prints warnings instead of enforcing.
#       disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of these two values:
#       targeted - Targeted processes are protected,
#       mls - Multi Level Security protection.
SELINUXTYPE=targeted