How can I set up password-less SSH login?

Question

I want to be able to login to a remote via ssh without having to enter the password all the time.

• How do I set it up?
• Is a different command required to execute a password-less session?

Answer 1

Answer

Execute these two commands:

ssh-keygen

Then you'll need to copy the new key to your server.

After the key is copied, ssh into the machine as normal

ssh user@host

You can now login without entering a password from the particular machine you executed the commands at.

Example

not-marco@rinzwind-desktop:~$ ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/home/not-marco/.ssh/id_rsa): 
Created directory '/home/not-marco/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/not-marco/.ssh/id_rsa.
Your public key has been saved in /home/not-marco/.ssh/id_rsa.pub.
The key fingerprint is:
b1:25:04:21:1a:38:73:38:3c:e9:e4:5b:81:e9:ac:0f not-marco@rinzwind-desktop
The key's randomart image is:
+--[ RSA 2048]----+
|.o= . oo.        |
|*B.+ . .         |
|*=o .   o .      |
| = .     =       |
|. o     S        |
|E.               |
| o               |
|  .              |
|                 |
+-----------------+
not-marco@rinzwind-desktop:~$ ssh-copy-id not-marco@127.0.0.1
not-marco@127.0.0.1's password: 
Now try logging into the machine, with "ssh 'not-marco@127.0.0.1'", and check in:

  ~/.ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

Explanation

This assumes you already have successfully connected to your server via SSH.

You'll need to generate an SSH Keypair which will allow you to identify you as yourself without using a password. You can opt to protect keys with a passcode if you wish, but this can be left blank allowing totally password-less SSH access.

First create your SSH Keypair by running ssh-keygen this will create an id_rsa and id_rsa.pub file. The pub file is what goes on the servers, the private key (id_rsa) is what stays with you and is how you identify yourself.

Next copy the public key to your server with ssh-copy-id user@server replacing user with your remote user and server with the machine DNS name or IP address. It'll prompt for your SSH password, enter it and if all completes successfully you'll be able to access the machine via ssh user@server without needing a password.

References

• https://help.ubuntu.com/community/SSH/OpenSSH/Keys

Answer 2

I normally use sshpass for that, install it with sudo apt-get install sshpass and use it like this

sshpass -p 'password' ssh your_username@your_server

Answer 3

If you create a public/pricate keypair und log in using the public key method you will not need to type your password. That is depending on the configuration of your key-ring and ssh agent.

Here is one of many short howtos for you. It is of crucial importance to the safety of this method, that the thusly generated private key remains private!

Answer 4

The way I usually do this is as follows:

ssh-keygen -t rsa

(When prompted for a password, leave it blank)

Then: cat ~/.ssh/id_rsa.pub | ssh username@hostname 'cat >> .ssh/authorized_keys'

(This requires the folder .ssh to be in the home directory on the targeted hostname, with the authorized_keys file in it)

Of course, replace username with the desired username, and hostname with the desired hostname or IP address

After that, just SSH to that box just like you're used to.

Answer 5

Type the following commands:

1. ssh-keygen

   Press Enter key till you get the prompt

2. ssh-copy-id -i root@ip_address

   (It will once ask for the password of the host system)

3. ssh root@ip_address

Now you should be able to login without any password.