前言

在日常的服务器管理和开发工作中，我们每天可能需要无数次地登录远程服务器。传统的密码登录方式不仅繁琐——需要我们记住并输入复杂的密码，更重要的是，它将我们的服务器暴露在被暴力破解的风险之下。

有没有一种方法，既能让我们安全地连接服务器，又能免去重复输入密码的烦恼呢？

答案是肯定的。那就是使用 SSH 密钥对进行身份验证。这篇博客将带你一步步配置 SSH 密钥登录，让你的服务器连接既安全又高效。

谷歌云服务器默认登录方式是browser ssh，但是有时候我们需要第三方客户端使用ssh连接服务器。
本文介绍如何使用ssh连接Google Cloud平台的虚拟机(云服务器)

1: Create a new key pair

1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
2. In the navigation pane, choose Key Pairs.
3. Choose Create key pair.
4. For Key pair name, enter a name for the new key pair, and then choose Create key pair.
5. Your browser will download the private key file automatically. The private key file is automatically downloaded by your browser. The base file name is the name you specified as the name of your key pair, and the file name extension is .pem. Save the private key file in a safe place.
6. Choose Close.
7. Important: You can create a key pair only once. Be sure to save the private key file to your computer. You’ll need to provide the name of your key pair when you launch an instance and the corresponding private key each time you connect to the instance.

2: Connect to your instance

1. Open a terminal window.
2. Use the cd command to navigate to the directory where your private key file is located.
3. Use the following command to set the permissions of your private key file so that only you can read it:

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chmod 400 /path/my-key-pair.pem

4. Use the following command to connect to your instance. Replace ec2-user with the appropriate user name for your AMI.

• For Amazon Linux 2 or the Amazon Linux AMI, the user name is ec2-user.
• For a CentOS AMI, the user name is centos.
• For a Debian AMI, the user name is admin.
• For a Fedora AMI, the user name is ec2-user or fedora.
• For a RHEL AMI, the user name is ec2-user or root.
• For a SUSE AMI, the user name is ec2-user or root.
• For an Ubuntu AMI, the user name is ubuntu. Here my OS is Ubuntu.
• Otherwise, if ec2-user and root don’t work, check with your AMI provider.

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ssh -i /path/my-key-pair.pem user_name@ip_address

3: (Optional) Connect to your instance using a password

1. Open a terminal window.
2. Use the following command to connect to your instance.

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ssh user_name@my-instance-ip

I meet Permission denied (publickey) error.

To fix it.

Step1: Firstly I need to use the previous command to connect to my instance.

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ssh -i /path/my-key-pair.pem user_name@ip_address

Step2: Set up a password for the user using passwd command along with the username.

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sudo passwd ubuntu

Step 3: Edit sshd_config file.

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sudo vim /etc/ssh/sshd_config

Find the Line containing PasswordAuthentication parameter and change its value from no to yes.

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PasswordAuthentication yes

If you want to set up root login, find PermitRootLogin parameter and change its value from prohibit-password to yes

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PermitRootLogin yes

After this changes save file and exit.

Step 4: Restart the SSH service.

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service ssh restart ## for ubuntu

service sshd restart ## for centos

Step 5: Add the .pem file to Local ssh.

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chmod 400 /path/my-key-pair.pem
ssh-add -k /path/my-key-pair.pem

Step 6: Now you can connect to your instance using a password.

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ssh user_name@my-instance-ip