服务器上所开放的端口就是潜在的通信通道，也就是一个入侵通道。对目标计算机进行端口扫描，能得到许多有用的信息，进行端口扫描的方法很多，可以是手工进行扫描、也可以用端口扫描软件进行。

扫描器通过选用远程TCP/IP不同的端口的服务，并记录目标给予的回答，通过这种方法可以搜集到很多关于目标主机的各种有用的信息，例如远程系统是否支持匿名登陆、是否存在可写的FTP目录、是否开放TELNET服务和HTTPD服务等。-opened by the server port is a potential communication channel, which is a channel invasion. The target computer port scan be useful information for a port scan many ways, it can be manually scan also use port scanning software. Through the use of scanners remote TCP / IP ports of different services, and to record the answers given by the target, this method can collect a lot of the target host of useful information, such as whether the remote system support anonymous landing, and whether there can write the FTP directory, whether to open the TELNET services and HTTPD services.