Host.allow deny(tcpwrap)

/etc/hosts.allow
sshd:1.1.1.1
/etc/hosts.deny
sshd :  all:spawn echo "`date` from %a to %A want access my sshd!" >> /tmp/sshd.log

禁止除了1.1.1.1的所有ip,并在登录失败时执行写入日志命令