如：开启ORACLE监听后，在本机使用nmap 127.0.0.1是可以扫描到1521端口的，实际上，在局域网内部的其他机器上，可能访问不了，需要配置防火墙才可以。
[redis@localhost redis]$ ./redis-server redis.conf --启动redis
[redis@localhost redis]$ telnet 127.0.0.1 6379 --尝试telnet
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is ‘^]‘.--成功
quit
+OK
Connection closed by foreign host.
[redis@localhost redis]$ ./redis-cli --进入客户端
127.0.0.1:6379> set foo bar--执行redis命令
OK--成功
127.0.0.1:6379> quit
[redis@localhost redis]$ nmap 127.0.0.1--使用nmap扫描却扫描不到6379端口 不知为何
Starting Nmap 6.40 ( http://nmap.org ) at 2017-05-29 09:43 CST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00092s latency).
Not shown: 997 closed ports
PORT STATE SERVICE
22/tcp open ssh
25/tcp open smtp
111/tcp open rpcbind
Nmap done: 1 IP address (1 host up) scanned in 0.08 seconds
