Introduction - If you have any usage issues, please Google them yourself
Port scanning technique commonly used there are many, such as the TCP connect () scanning, TCP SYN scanning, TCP FIN scanning, network, there are many articles devoted to, for example: http://www.antai-genecon.com/suml/zhishiyy/jingong/duankougj.htm on introducing many of my procedures used by the most basic scanning techniques: TCP scanning