I believe the sshd directives to configure the daemon to use keys only for authentication is mostly all that's required to disable passwords.  I've used this before.  Be aware that it only affects using passwords to access the system via ssh though. You will also see password attempts failing in your logs from all the attacks your servers face.

You would still need user passwords for sudo access. To remedy that, there are two relatively simple methods, both have security flaws.

1. Disable password challenges in sudo rules, which I think is a horrible idea for security.

2. Use pam_ssh_agent_auth module and pam_sudo, and use ssh key agents on the clients. This will make sudo authenticate that the agent's key matched the user's authorized key for the authentication challenge. I don't presume to think this can't be compromised, but it's a workable solution and better than passwordless sudo.

On Jun 12, 2017 9:18 AM, "McIntyre, James T. (Farragut Suitland, MD)" <jmcintyre@nmic.navy.mil> wrote:
Not sure I understand the complete question.

We do person by person as in loading up authorized_keys with the personal
rsa.pub key such as:
cat .ssh/id_rsa.pub | ssh b@B 'cat >> .ssh/authorized_keys'.  Will ask you for
password to complete the task.  Once done, should not ask for password until
key changes.

The .ssh lives in the home folder of each user so that each user has a unique
key loaded into their remote home folder.

This gives us passwordless ssh as well as positive identity of each individual
to load them into the proper account.  Same goes for root so that root will
ssh into root.

Recompiling, must not.  Positive ID, must have.

Am I way off base?

-----Original Message-----
From: Shawn Wells [mailto:shawn@redhat.com]
Sent: Thursday, June 08, 2017 10:28 PM
To: scap-security-guide@lists.fedorahosted.org
Subject: [Non-DoD Source] Re: Disabling passwords in the cloud



On 6/8/17 9:38 AM, Brent Kimberley wrote:


        Does sshd need to be recompiled - in order to completely disable password
authentication?



        I would like to reduce the number of false positives in /var/log/secure

        ^.*sshd.*: Invalid user .* from .*$

        ^.*sshd.*: reverse mapping checking getaddrinfo for .* failed - POSSIBLE
BREAK-IN ATTEMPT!$

        ^.* sshd.*: input_userauth_request: invalid user .*$


In theory, should be able to disable ChallengeResponseAuthentication and
PasswordAuthentication, then call it a day. Never actually tried, though.

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