Copy user's SSH ID to another user

I have login with root on a client server and use "su - u user1" to stimulate the user. Afterwards, I use "ssh-keygen -t rsa".

Afterwards, I use "ssh-copy-id -i server" to copy the user's key to another server. It ask for the user password.

However, I don't have the user's password and hence, I can't copy the keys to the server. What can I do ?
(actually, I have use root to copy the keys to the user 's .ssh directory but it doesn't work).

Any advise ? Tks
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Zephyr ICTCloud ArchitectCommented:
Did you adjust the rights and owner on the ssh keys after copying them to the other user's directory?

Also when you copy over the key to another server, is it the user password or the root password of the other server it's asking?
AXISHKAuthor Commented:
it ask for user password but I do not have it
Zephyr ICTCloud ArchitectCommented:
Can't you try copying it to the root account on the other server with the root user?
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I'll clarify a bit more on what spravtek mentions.

It shouldn't ask if you're logged in to root or connected to root when you do the copying.  If you're not using root, then you must have the user account's password first, or you'll need to have the user do it for you.

When you copy the ssh key to the other account, you also need to set the owner of the key file to that new user.
  chown -R user2 ~user2/.ssh/
AXISHKAuthor Commented:
policy do not allow root to ssh to another user
Then how did you copy the file as root, as you've mentioned in the original question?
AXISHKAuthor Commented:
so use root account to copy files under the user's .ssh folder to the corresponding. user folder on remote server.Grant the permission then, correct
Zephyr ICTCloud ArchitectCommented:
That's a possibility yes ... You can test that.
Yes.  If you don't have the account password, and you have root, then that's the only way.
AXISHKAuthor Commented:
Still doesn't work...

There are 3 keys - id_rsa, and known_hosts have been copied to the remote server. And already changed the group (chown) and permission (chmod 644) to these files. Try again to ssh to the remote server with the user but it still asked for password. Any idea ?

You only need to copy the public key to the remote server and place it in the authorized keys file.

cat >> ~user2/.ssh/authorized_keys

If this is the first time you've created the flie, you also need to change the owner.
chown user2 ~user2/.ssh/authorized_keys

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AXISHKAuthor Commented:
Done. when ssh user1@remoteserver, it seem to connect but it cut off automatically... Any idea ?/
Zephyr ICTCloud ArchitectCommented:
Set logging on when doing the ssh, that might give us a clue, like this:

ssh user1@remoteserver -vvvv

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