ssh login without password

First log in on 192.168.30.72 as user user1 and generate a pair of authentication keys. Do not enter a passphrase:


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user1@192.168.30.72:~> 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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user1@192.168.30.72:~> ssh user1@192.168.30.178 mkdir -p .ssh

user1@192.168.30.178's password:

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Finally append a's new public key to user1@192.168.30.178:.ssh/authorized_keys and enter user1's password one last time:

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user1@192.168.30.72:~> cat .ssh/id_rsa.pub
ssh user1@192.168.30.178 'cat >> .ssh/authorized_keys'

user1@192.168.30.178'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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user1@192.168.30.72:~> ssh user1@192.168.30.178