vi /etc/hosts.allow
# hosts.allow This file contains access rules which are used to
# allow or deny connections to network services that
# either use the tcp_wrappers library or that have been
# started through a tcp_wrappers-enabled xinetd.
#
# See 'man 5 hosts_options' and 'man 5 hosts_access'
# for information on rule syntax.
# See 'man tcpd' for information on tcp_wrappers
#下面為允許通過制定ip訪問服務器
sshd:xxx.xxx.xxx.xxx:allow
sshd:xxx.xxx.xxx.xxx:allow
sshd:172.16.0.0/255.255.0.0:allow
sshd:192.168.0.0/255.255.0.0:allow