Jenkins continuous integration: two machines in the Linux system log in to each other without secrets

background knowledge

We put the public key in the appropriate location of the remote system, and then start the ssh connection from the local .

At this point, the remote sshd will generate a random number and encrypt it with the public key we generated and send it to the local, and the local will decrypt it with the private key and send the random number back to the remote system.

Finally, sshd on the remote system will conclude that we have a matching private key and allow us to log in

The above method is widely used on Linux systems. For example, when Jenkins builds continuous integration, it needs to remotely log in to several other machines to copy the packaged results. In this case, password-free login is required.

The following is the introduction of the steps and conditions for two Linux systems to realize password-free login.

1. The principle of machine A password-free login to machine B

1. First generate a pair of secret keys (ssh-keygen) on machine A, copy the public key to machine B, and rename authorized_keys;

2. Machine A sends a connection request to machine B, and the information includes username and ip;

3. When machine B receives the request, it will search from authorized_keys to see if it has the same username and ip. If so, machine B will randomly generate a string;

4. Then use the public key to encrypt, and then send to machine A;

5. After machine A receives the information from machine B, it will use the private key to decrypt, and then send the decrypted string to machine B;

6. After machine B receives the information sent by machine A, it will compare the previously generated character strings, and if it is consistent, it will allow password-free login.

2. Centos7 has ssh service installed by default

3. Start the ssh service

# 查看 ssh 状态
systemctl status sshd
# 启动 ssh
systemctl start sshd
# 停止 ssh
systemctl stop sshd

4. serverA generates a secret key

[root@localhost ~]# ssh-keygen

CentOS7 uses the RSA encryption algorithm to generate a key pair by default, which are stored in id_rsa (private key) and id_rsa.pub (public key) in the ~/.ssh directory. You can also use the "-t DSA" parameter to specify the DSA algorithm, and the corresponding files are id_dsa and id_dsa.pub. During the key pair generation process, you will be prompted to enter the private key encryption password, and you can directly press Enter without password protection.

5. Move the id_rsa.pub file

1. Copy the file id_rsa.pub in the ~/.ssh directory of machine A to the ~/.ssh directory of machine B you want to log in

scp ~/.ssh/id_rsa.pub 192.168.0.101:~/.ssh/

 2. Then run the following command on machine B to import the public key into the file ~/.ssh/authorized_keys

cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys

3. In addition, please note that it must be installed on the server. This is a security requirement of Linux. If the permissions are incorrect, automatic login will not take effect.

~/.ssh permissions set to 700

chmod -R 777 ~/.ssh

The permission of ~/.ssh/authorized_keys is set to 600

chmod -R 600 ~/.ssh/authorized_keys

6. Verify password-free login

ssh 机器B的ip

Finally, I would like to thank everyone who has read my article carefully. Reciprocity is always necessary. Although it is not a very valuable thing, you can take it away if you need it:

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