SSH, Secure SHell, was designed and created to provide the best security when accessing another computer remotely.

Not only does it encrypt the remote session, it also provides better authentication facilities, as well as features like secure file transfer and network port forwarding so that you can increase the security of other network protocols. 

使用username/pwd来连接远程机器，不够安全，密码可能被截取。用SSH的好处是会加密，方法是用putty客户端。而另一种更高级的方法是SSH private/public key pair，而且Pageant可以记住passphrase来自动连接每一次session。

1, To use SSH on Windows, you have to download an SSH client. One of the best and freely available clients is called PuTTY. 

2, A common usage of SSH is for transfering files. Under Windows, the best program to use for these is another program based on the implementation of PuTTY, called WinSCP. 

3, Generating an SSH key is an optional thing. You can continue to use your server side password and be fine. However, it is more secure to use a private/public key pair with a passphrase and more options will be available to you by doing so.

4，Pageant: Once you‘ve entered the passphrase, all SSH based sessions using PuTTY or WinSCP, will use the agent to decrypt the private key for authentication. This means that you will not have to enter your password or passphrase anymore until you logout of your machine, close Pageant or tell Pageant to forget about the passphrase for the key.