SSH: completly disabling password authentication

Question

is there a way to disable password authentication completely? The command line is the following:

ssh -o KbdInteractiveAuthentication=no -o PasswordAuthentication=no machine" 

it STILL asks for a password. Of course I would like to do this without touching the server, if possible.

Solution 1

Okay, I've found it! It's

ssh -o BatchMode=yes host

Not very intuitive, especially with the fact that the options I tried previously don't work.

Solution 2

You can add those option to .ssh/config and save some typing:

Host host
BatchMode yes

should do the job.

Solution 3

I just had this problem and found the answer here:

http://www.gossamer-threads.com/lists/openssh/dev/47179

Basically, openssh used keyboard-interactive to implement challenge-repsonse. So if either of these options are set to "yes", then keyboard-interactive gets set to "yes" in the code. You have to set both to "no" in order to get the behavior you want.

I had to do:

ssh -o PasswordAuthentication=no -o KbdInteractiveAuthentication=no -o ChallengeResponseAuthentication=no

Of course, the BatchMode=yes setting would take care of all of these for you and future proof you against any new user interactive authentication methods in the future.