禁止root远程登录
vi /etc/ssh/sshd_config
PermitRootLogin yes改为PermitRootLogin no
重启sshd服务
service sshd restart
ssh和vsftp限制IP登录白名单和黑名单
* 修改文件：/etc/hosts.deny，加上最后两行，阻止所以进入,如下：
# hosts.deny This file describes the names of the hosts which are
# *not* allowed to use the local INET services, as decided
# by the '/usr/sbin/tcpd'
