把私钥文件保存为keyfile.ppk，放在MyEnTunnel同一目录下，然后打开MyEnTunnel，勾选Settings里面的Use Private Key。

如下图所示：

PS：如何将EC2的pem密钥转为ppk的？

This is easy to do with PuTTYGen.

1. Download your .pem from AWS

2. Open PuTTYgen

3. Click "Load" on the right side about 3/4 down

4. Set the file type to *.*

5. Browse to, and Open your .pem file

6. PuTTY will auto-detect everything it needs, and you just need to click "Save private key" and you can save your ppk key for use with PuTTY