1 /etc/hosts.allow-
1 if allow will not check 2
2 if not found then go to 2
2 /etc/hosts.deny .
2 if not found allow access.
以下例子是只允许 192.168的c段访问ssh，其他deny：
[root@localhost etc]# more hosts.allow
sshd:192.168.0.0/255.255.255.0
[root@localhost etc]# more hosts.deny
sshd:ALL