简单控制访问ip,hosts.allow/hsots.deny

brief

a simple access control language that is based on client (host name/address, user name), and server (process name, hostname/address) patterns.

hosts.allow

格式：
serivce: [client]: [action]
    serivce: 被控制服务名
    client: 客户端主机名、IP地址(支持通配 * .)  ALL/172.
    action: 动作 ALLOW/DENY 
    
ALL   //所有
LOCAL //本地

172.24.0.  == 172.24.0.0/255.255.255.0 == 172.24.0.*

例子

/etc/hosts.allow
sshd: 172.24.20.*: ALLOW

/etc/hosts.deny
sshd: 10.10.:DENY

or
/etc/hosts.allow  
sshd: 172.24.20.     //默认ALLOW

/etc/hosts.deny
sshd: 10.10.        //默认DENY

/etc/hosts.allow
# 仅允许172.24.0.网段的IP访问
ALL:172.24.0.:ALLOW  

/etc/hosts.deny
# 所有阻止
ALL:ALL:DENY

linux系统会先检查/etc/hosts.allow规则，再检查/etc/hosts.deny规则，如果有冲突优先按照/etc/hosts.allow规则处理