我剛發覺建立webapi,要照著步驟去做

我照著做一個新的webapi 名稱為web03
```
cd web03
dotnet new webapi
dotnet add package Microsoft.EntityFrameworkCore.SqlServer
dotnet add package Microsoft.EntityFrameworkCore.InMemory
```

編譯執行沒有問題
```

D:\csharp\web03>dotnet build
Microsoft (R) Build Engine for .NET 16.9.0+57a23d249 版
Copyright (C) Microsoft Corporation. 著作權所有，並保留一切權利。

正在判斷要還原的專案...
所有專案都在最新狀態，可進行還原。
web03 -> D:\csharp\web03\bin\Debug\net5.0\web03.dll

建置成功。
0 個警告
0 個錯誤

經過時間 00:00:02.85

D:\csharp\web03>dotnet run
正在建置...
info: Microsoft.Hosting.Lifetime[0]
Now listening on: https://localhost:5001
info: Microsoft.Hosting.Lifetime[0]
Now listening on: http://localhost:5000
info: Microsoft.Hosting.Lifetime[0]
Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
Content root path: D:\csharp\web03
```

https://localhost:5001/WeatherForecast 執行沒問題
https://127.0.0.1:5001/ 網頁也可以正常了

然後終端機 打指令

eric@ubserver:~/csharp/web02$ nc -v 127.0.0.1 5000
Connection to 127.0.0.1 5000 port [tcp/*] succeeded!
^C
eric@ubserver:~/csharp/web02$ sudo nmap 127.0.0.1
[sudo] eric 的密碼：
Starting Nmap 7.80 ( https://nmap.org ) at 2021-04-01 16:49 CST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000010s latency).
Not shown: 996 closed ports
PORT STATE SERVICE
80/tcp open http
631/tcp open ipp
5000/tcp open upnp
5001/tcp open commplex-link

Nmap done: 1 IP address (1 host up) scanned in 0.15 seconds
eric@ubserver:~/csharp/web02$

正常拉