4

Somewhere I read that to access a remote machine through SSH we need to copy ~/.ssh/id_rsa.pub of the local machine to ~/.ssh/authorized_keys of the remote machine. I did this and I can access remote machine through ssh.

I want the remote machine to be accessible from multiple servers, like: Machine A can access machine B, and there is another machine C which can also access machine B.

I copied ~/.ssh/id_rsa.pub of machine A to ~/.ssh/authorized_keys of machine B and I can access machine B.

But I also want to access machine B from machine C then what should I do? I mean, where should I copy ~/.ssh/id_rsa.pub of machine C to machine B so that I can access machine B from machine C?

9

The authorized_keys file on a remote host can contain more than just one public key. Just append them – make sure that each key gets a new line.

To simplify this process, there is ssh-copy-id(1).

ssh-copy-id user@machine-B

You can execute the above command on Machine C. It will copy the default public key to Machine B and append it to authorized_keys automatically. You can also specify another public key to be copied by using the -i option if you want.


Here's the reference in the manual:

The user creates his/her key pair by running ssh-keygen(1). This stores the private key in […] ~/.ssh/id_rsa.pub (protocol 2 RSA) in the user's home directory. The user should then copy the public key to ~/.ssh/authorized_keys in his/her home directory on the remote machine.

The authorized_keys file […] has one key per line, though the lines can be very long. After this, the user can log in without giving the password.

  • thanks for your reply but ssh-copy-id user@machine-B command is not working. Its giving error "ssh-copy-id: command not found". – Amrinder Singh Mar 14 '12 at 5:50
  • Then you have to install it. It doesn't come with every system. – slhck Mar 14 '12 at 8:03
3

Alternatively, you can run this command:

cat id_rsa.pub | ssh remote-user@remote-host "cat >>~/.ssh/authorized_keys"

In order to append to the authorized_keys file

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.