How about Linux Server SSH password not required

The following steps take the root user as an example. The owner of the script execution takes the same steps as the actual application.

1.Log On As root from A and B respectively and run ssh-keygen to create A directory in/root. ssh and generate the dsa key pair. Press ENTER twice when passphase is prompted. This will generate/root/. ssh/id_dsa and/root/. ssh/id_dsa.pub.
Ssh-keygen-t dsa output: Generating public/private dsa key pair.
Enter file in which to save the key (/home/sj/. ssh/id_dsa ):
Enter passphrase (empty for no passphrase ):
Enter same passphrase again:
Your identification has been saved in/home/sj/. ssh/id_dsa.
Your public key has been saved in/home/sj/. ssh/id_dsa.pub.
The key fingerprint is:
1b: 8c: 3d: 6d: eb: e3: 10: c3: b7: c0: 68: a3: 5f: 7e: b3: 51 sj@192.168.0.1
2.Test it first. log on from A as root and enter # ssh B. A prompt of root password will be prompted.

3.Add the public key of a to the. ssh/authorized_keys file of B. If the authorized_keys file does not exist, copy the Public Key directly. For example:
Run scp/root/. ssh/id_dsa.pub:/root/. ssh/authorized_keys. The file name must be correct.

4.Run # ssh B from A now without the password.

　

Basic Principles:
If you want to SSH from user A as user user1 to user B as user user2, if you want to use RSA key pair authentication and do not need A password, then the ssh background program on user B will take out ~ User2 /. the RSA public key related to A in ssh/authorized_keys is used to challenge the ssh client program running as user1 on. copy pub to B as authorized_keys. Then A maintains the Private Key identity, And the sshd on B takes out the public key of A to challenge. Therefore, to succeed, you can add A lot of lines to authorized_keys to allow the public keys of other servers to be added.

Examples of common applications:
1. use user rootSSH on user A to user B as normal user rather than root. For security purposes, sometimes you do not need to act as root. You only need to act as normal user without A password to complete relevant work.

Log on to A as the root user. A # scp/root /. ssh/identity. pub href = "mailto: user @ B:/home/user /. ssh/authorized_keys "> user @ B:/home/user /. ssh/authorized_keys
2. tar A batch of files from A to B. A # tar cvf-/etc | (ssh B tar xvf -)
3. run cronjob on A, modify A file, and upload it to B0 1 *** cat/etc/shadow | awk-F: '{print $1 ": "$2} '| (ssh B' cat>/home/passwd ')

FAQs:
1. This SSH method requires the direct root login (PermitRootLoginyes) allowed in sshd_config on B ).
2. I have server A and other server B, C, D. I want to switch from ASSH to these servers but not automatically. It is better to enter RSA passphase, but it is too troublesome. What should I do?
A. Enter passphase when running ssh-keygen on server.
B. log on to A and run A # ssh-agent bash.
C. Run ssh-add and passphase to enter the memory.
D. Run ssh B or SSH C or SSH D again, and the password is no longer required. You only need to enter the password pair once.
E. Enter ssh-agent-K before exiting the shell.