This is NOT about public key authorization, I know how to copy the public key and ssh that way. This is about the private key.

So I just created 2 VMs, they're connected through vagrant private network. One of them is called server01 the other is called server02.

I created user '01' on 'server01', and user '02' on 'server02'.

I ssh-keygen on both of them, so they each have id_rsa and id_rsa.pub.

I copy the contents of 01's id_rsa (the private key) into a file called 01key in 02's machine.

I then ssh into 01 from 02 with the following command: ssh -i 01key 01@ And it asks me for the password....

Why? Isn't the whole point of connecting with the private key that you DON'T use passwords? I created a Linux server on AWS and it provided me with a private key for that particular instance and I was able to ssh -I key into it without it asking for the password, so what am I doing wrong?

I checked the permissions on the 01key file, and they're 600.

EDIT: All the answers are irrelevant. I know how to use the public key to connect through ssh, but that's not what I'm looking for.

I created a Linux instance on AWS and created an ssh keypair, then it only gave me the PRIVATE key, which I could use to connect to that AWS instance. That's what I'm talking about.

3 Answers 3


I copy the contents of 01's id_rsa (the private key) into a file called 01key in 02's machine.

Pubkey authentication doesn't work like that. You must copy user01's public key to


on server02. This is more easily done via the command:

ssh-copy-id user01@server02

I then ssh into 01 from 02 ...

That's the opposite, with this setup you can ssh from server01 to server02 passwordlessly.

... with the following command: ssh -I 01key 01@

The -I flag specifies the PKCS#11 shared library. You probably meant -i to specify the identity. Anyway, this is unnecessary; just do

ssh user01@server02
  • I know how to use the pubkey to connect. I know how to use the ssh-copy-id command. The I was a typo. This does not answer my question.
    – iamAguest
    Aug 30, 2018 at 6:11

To copy the public key to a server use:

ssh-copy-id user2@server

wich will copy (on current server):


into the file (on specified server):


This can also be done manually by appending public key:

cat /home/user1/.ssh/id_pub.rsa | ssh user2@server "cat >> /home/user2/.ssh/authorized_keys"

  • cat /home/user1/.ssh/id_pub.rsa pipes contents of user1's public key

  • ssh user2@server "[cmd]" execute specified command as user2 on specified server

  • cat >> /home/user2/.ssh/authorized_keys takes piped data and appends to file


You aren't supposed to copy the private key. It's id_rsa.pub you want, and usually you would put that in ~02/.ssh/authorized_keys.

  • Yes I was able to create a user called 01, and another called 02 on the other machine. The AWS server gave me it's private ssh key, which I used to connect to it without it asking for my password. I know how to ssh with the public key, with that method 02 would give his public key to 01 and append it to the authorized_keys file, and then 02 would connect to 01, but that's work on 01's part, which is not what happened on the AWS server.
    – iamAguest
    Aug 29, 2018 at 15:33
  • Alright, I will be interested to read the answer if it's forthcoming. Aug 29, 2018 at 15:39
  • 1
    Now that you have two additional answers not substantially different from mine, one from a user of high rep. Aug 29, 2018 at 20:20

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