转载：ssh远程登陆服务器免密码的方式

Step 1: Generate a key pair on the local server

Use ssh-keygen to generate authentication keys for SSH.

$ ssh-keygen

Output:

Generating public/private rsa key pair.
Enter file in which to save the key (/home/user/.ssh/id_rsa): 
Created directory '/home/user/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/user/.ssh/id_rsa.
Your public key has been saved in /home/user/.ssh/id_rsa.pub.
The key fingerprint is:
8c:2a:ed:82:98:6d:12:0a:3a:ba:b2:1c:c0:25:be:5b

Step 2: Install your public key on the remote server

Use ssh-copy-id to connect to the remote machine and install your public key by adding it the authorized_keys file.

$ ssh-copy-id -i ~/.ssh/id_rsa.pub UserName@RemoteServer

Output:

UserName@RemoteServer's password: ********
Now try logging into the machine, with "ssh 'username@remoteserver'", and check in:
~/.ssh/authorized_keys
to make sure we haven't added extra keys that you weren't expecting.

Step 3: Add a private key to the authentication agent on the local server

Use ssh-add to add identities to the ssh-agent – the authentication agent.

$ ssh-add

Output:

Identity added: /home/user/.ssh/id_rsa (/home/user/.ssh/id_rsa)

Now you can log into the remote server via the SSH protocol without prompting a password.

转载 https://www.shellhacks.com/ssh-login-without-password/