Question

After your browser acquires the correct IP address, it will attempt to connect to that IP address via a port. A port is a logical division on devices that identifies a specific network service. We identify ports by their port numbers, which can range from 0 to 65,535.

浏览器获取正确的 IP 地址后，会尝试通过端口连接到该 IP 地址。端口是设备上用于标识特定网络服务的逻辑分区。我们通过它们的端口号来识别端口，端口号的范围从 0 到 65,535。

Ports allow a server to provide multiple services to the internet at the same time. Because conventions exist for the traffic received on certain ports, port numbers also allow the server to quickly forward arriving internet messages to a corresponding service for processing. For example, if an internet client connects to port 80, the web server understands that the client wishes to access its web services ( Figure 3-3 ).

端口允许服务器同时向互联网提供多个服务。由于某些端口上接收到的流量已经有了惯例，端口号还使服务器能够快速将到达的互联网消息转发给相应的服务进行处理。例如，如果互联网客户端连接到端口 80，则 Web 服务器会明白客户端希望访问其 Web 服务（图 3-3）。

Figure 3-3 : Ports allow servers to provide multiple services. Port numbers help forward client requests to the right service.

图 3-3：端口允许服务器提供多个服务。端口号帮助将客户端请求转发到正确的服务。

By default, we use port 80 for HTTP messages and port 443 for HTTPS, the encrypted version of HTTP.

默认情况下，HTTP 消息使用端口 80，HTTPS 消息使用端口 443，HTTPS 是 HTTP 的加密版本。