Network Port Scanning Techniques

If you wanna install a service in a server computer, there will be a new port added in this server. That is to say, an entrance will confront to all users, Any users can connect this server from client computer through this port. Meanwhile, if there is a bug in this server software, hacker can crack this computer by this port. So we should find these bugs before hacker."Port scan" means show whether a port is active or not by scan every ports one by one. If one service is active, show its version and its bugs.There has been many port scan free softwares, but they often exists too much limit to use.this thesis put focus in any kind of port scan technologies. At first, assort of port scan, history of port scan etc. Then introduce some advanced port scan theory, e.g. TCP scan, UDP scan, ICMP scan. At last , I designed a programme to realize these advanced port scan theories.