Suppose we have two computers: computer1 with ip 10.0.0.1 and computer2 with ip 10.0.0.2. We connect very frequently from computer1 to computer2 using SSH. As we connect very frequently, entering the password every time we connect becomes a repetitive task and a waste of time. In order to be able to connect between them without password, in a comfortable and secure way, we can do it using RSA keys instead.
Connection between computers
To be able to connect via SSH using the RSA keys instead password:
We generate the public and private RSA keys on computer1:
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rubenhortas@computer1:~/.ssh$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/rubenhortas/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/rubenhortas/.ssh/id_rsa.
Your public key has been saved in /home/rubenhortas/.ssh/id_rsa.pub.
The key fingerprint is:
**:**:**:**:**:**:**:**:**:**:**:**:**:**:**:**
The key's randomart image is:
*You have to leave the passphrase empty, otherwise it will ask for it every time we connect to computer2 via SSH
We copy the public key from computer1 to computer2:
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rubenhortas@computer1$ ssh-copy-id -i ~/.ssh/id_rsa.pub 10.0.0.2
The authenticity of host '10.0.0.2 (10.0.0.2)' can't be established.
RSA key fingerprint is **:**:**:**:**:**:**:**:**:**:**:**:**:**:**:**.
Are you sure you want to continue connecting (yes/no)? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
rubenhortas@10.0.0.2's password:
Finally, we connect from computer1 to computer2 using SSH and checking that it does not ask us for the password.
Enjoy! ;)