Creating user specific authentication methods in SSH

Question

1. I have configured sshd on an Ubuntu server to use key authentication and it is working fine.
2. I had to disable password authentication for key authentication to work.
3. Server is always accessed via remote terminals or putty.

Now all user accounts are able to login with the authentication key and passphrase. But now I want to create only one new user without key authentication. So how should I go about doing this in such a way that does not hamper other users who are using key authentication.

Answer 1

You can enable password and key-authentication at the same time, they are not exclusive.

Answer 2

You can use match in sshd_config to select individual users to alter the PasswordAuthentication directive for.

Match User root,foo,bar
    PasswordAuthentication no
Match User Rishee
    PasswordAuthentication yes

This would give root, foo and bar key authentication, and Rishee password authentication.

An alternative is to match by negation, like this:

PasswordAuthentication no
Match User !root
    PasswordAuthentication yes

In this case, everyone except root gets password authentication.

You can also match by group:

Match Group usergroup
    PasswordAuthentication no