端口扫描器, 开256个线程扫指定端口
* example...
*
* thread 0 1 2 ... 255
* 0 40.4.0.0 40.4.1.0 40.4.2.0 ... 40.4.255.0
* 1 40.4.0.1 40.4.1.1 40.4.2.1 ... 40.4.255.1
* 2 40.4.0.2 40.4.1.2 40.4.2.2 ... 40.4.255.2
* ... ... ... ... ... ...
* 255 40.4.0.255 40.4.1.255 40.4.2.255 ... 40.4.255.255