Linux Baidu Cloud Compute Setting Login Method

Background

This document explains how to configure Linux server login methods (key-based and password-based), using CentOS 7.6 as an example.

Set key-based login

Step I: Generate a key pair on the server.

Run "ssh-keygen -t rsa" on the client to generate a key pair. By default, the keys are stored in /root/.ssh, with no password set by default. You can customize the password and directories as needed.

1root@ins8o1pb:~# ssh-keygen -t rsa
2
3Generating public/private rsa key pair.
4Enter file in which to save the key (/root/.ssh/id_rsa):
5Enter passphrase (empty for no passphrase):
6Enter same passphrase again:
7Your identification has been saved in /root/.ssh/id_rsa.
8Your public key has been saved in /root/.ssh/id_rsa.pub.
9The key fingerprint is:
10SHA256:nBctW+aEbuFIDXeYQSmGqHAo4QFe6fWKjjBTBc9hL2Y root@instance-xh28o1pb
11The key's randomart image is:
12+---[RSA 2048]----+
13|++.o+. ...+=.    |
14|* +=o+. o+++     |
15|.=.oE o...* =    |
16|  o+ . + = X     |
17| .  . . S * .    |
18|+  . .   o       |
19|.oo              |
20| . .             |
21|                 |
22+----[SHA256]-----+

Check the files in the /root/.ssh directory. The private key is id_rsa, and the public key is id_rsa.pub.

Step II: Install the public key on the server.

Run the following command to install the public key on the server.

1root@ins8o1pb:~# cd .ssh
2root@ins8o1pb:~# cat id_rsa.pub >> authorized_keys

After completing the public key installation, ensure the file permissions are properly set to guarantee a successful connection.

1root@ins8o1pb:~# chmod 600 authorized_keys
2root@ins8o1pb:~# chmod 700 ~/.ssh

Step III: Set SSH and enable key-based login function.

1. Edit the file /etc/ssh/sshd_config, and conduct the following settings:

RSAAuthentication yes
PubkeyAuthentication yes

Additionally, observe whether the root user can sign in via SSH:

PermitRootLogin yes

2. After completing all settings and successfully logging in via Key, disable the password-based login:

PasswordAuthentication no

3. Finally, restart the SSH service.

1root@ins8o1pb:~# service sshd restart

Step IV: Download the private key to the client.

Transfer the private key file id_rsa to the client.

• Sign in to a Linux server
  using the putty client on Windows. Convert the private key format by opening putty key generator 工具-->File -> Load private key, and clicking save private key. The conversion is completed. Windows private keys typically end with .ppk, e.g., save as id_rsa.ppk.
• When signing in with a Putty key, perform the following operations after entering the server address:
  Enter the username in Auto-login username in the Connection -> Data interface;
  Browse to select the private key file id_rsa.ppk in Connection -> SSh -> Auth -> Private key file for authentication;
  Save these settings, and click Open to sign in to the server directly.

Set password-based login

If the password-based login is required, simply change PasswordAuthentication to yes in /etc/ssh/sshd_config.

1PasswordAuthentication yes