Your aim
You want to use Linux and OpenSSH to automize your tasks. Therefore you need an automatic login from host A / user a to Host B / user b. You don't want to enter any passwords, because you want to call ssh from a within a shell script.
How to do it
First log in on A as user a and generate a pair of authentication keys. Do not enter a passphrase:
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a
@A
:~> ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/a/.ssh/id_rsa):
Created directory
'/home/a/.ssh'
.
Enter passphrase (empty
for
no
passphrase):
Enter same passphrase again:
Your identification
has
been saved in /home/a/.ssh/id_rsa.
Your public key
has
been saved in /home/a/.ssh/id_rsa.pub.
The key fingerprint is:
3e:4f:05:79:3a:9f:96:7c:3b:ad:e9:58:37:bc:37:e4 a
@A
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Now use ssh to create a directory ~/.ssh as user b on B. (The directory may already exist, which is fine):
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a
@A
:~> ssh b
@B
mkdir
-p .ssh
b
@B
's password:
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Finally append a's new public key to b@B:.ssh/authorized_keys and enter b's password one last time:
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a
@A
:~> cat .ssh/id_rsa.pub | ssh b
@B
'cat >> .ssh/authorized_keys'
b
@B
's password:
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From now on you can log into B as b from A as a without password:
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a
@A
:~> ssh b
@B
hostname
B
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A note from one of our readers: Depending on your version of SSH you might also have to do the following changes:
- Put the public key in .ssh/authorized_keys2
- Change the permissions of .ssh to 700
- Change the permissions of .ssh/authorized_keys2 to 640
参考文章：SSH Passwordless Login Using SSH Keygen in 5 Easy Steps
http://www.tecmint.com/ssh-passwordless-login-using-ssh-keygen-in-5-easy-steps/
