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Is there a way to temporarily disable public key authentication when ssh'ing, and use password authentication instead?

I currently want to access remote server, but I'm using another laptop, not mine.

Browsing that link, I found that the command ssh -o PreferredAuthentications=keyboard-interactive -o PubkeyAuthentication=no host1.example.org doesn't work everywhere. And yes, it doesn't work for me. I'm using: OpenSSH_5.9p1 Debian-5ubuntu1, OpenSSL 1.0.1 14 Mar 2012

Edit: I also tried to type ssh -o PreferredAuthentications=password -o PubkeyAuthentication=no but still have "Permission denied (publickey)".

So, is there a specific configuration to do in the remote server, for that command to work? Or, when that command will work as expected?

Thanks a lot for advices.

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    If you followed the link again, there was someone stating that your method didn't work, but this did: ssh -o PreferredAuthentications=password -o PubkeyAuthentication=no
    – NickW
    Mar 28, 2013 at 15:03
  • @NikW Thanks a lot, maybe I should have mention it, tried the command you propose too, still have the "Permission denied (publickey)".
    – Nsukami _
    Mar 28, 2013 at 22:41
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    Just hit this problem because my laptop had a TON of keys, and ssh tried all of them, and I was rejected before even a chance to enter password. Thanks for asking.
    – Dallaylaen
    Dec 21, 2015 at 15:55
  • 3
    @NickW If you put your comment as the answer, I'd upvote it.
    – labyrinth
    Jan 6, 2016 at 22:22

3 Answers 3

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This sounds like a configuration issue on the server side.

If the server allows both public key and password authentication then even if you try to connect without a private key file present on the client, it should prompt you for a password.

If you are getting the error message "Permission denied (publickey)" then it sounds like password authentication is not supported on your server.

Without seeing the /etc/sshd_config file, it is difficult to know but my guess would be that you need to make sure the following line exists:

PasswordAuthentication yes

Restart the ssh server, and when you connect from the client you should be prompted for a password if there is no private key present, or if the private key doesn't match the public key on the server.

A more secure alternative to this of course would be to copy your private key to the laptop which you are using, or in-fact generate a new private key to be used on that laptop and add the public key to .ssh/authorized_keys

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    Please do not answer a question that wasn't asked. It makes it very annoying for other people finding this question from Google.
    – Timmmm
    Apr 8, 2020 at 13:57
58

If you want to bypass key authentication when logging to the server, just run:

ssh -o PubkeyAuthentication=no user@host
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    Doesn't fix the problem for me.
    – reinierpost
    Sep 28, 2020 at 13:37
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    This is what people are looking for when they search "ssh deactivate keys"
    – Kyle
    Jan 25 at 19:44
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Just make an ID file that is blank.

touch $HOME/.ssh/blank

If you leave the permission 640 or 644 then ssh will complain that the permissions are not secure enough and not use it. If you chmod it to 600, then it will prompt for a password 3 times and fail because there is no password. So just leave it 640 or 644.

Then when you ssh use this command.

ssh -i $HOME/.ssh/blank servername-or-ip

You could use .ssh/config and set a host entry to not use the key but it is less temporary or you could create aliases for server and server-nokey but it gets long and is a pain to maintain.

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    -i /dev/null works too, and doesn't need checking permissions.
    – svvac
    Jul 10, 2017 at 7:22
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    Blank/null files don't work, ssh says Load key "/dev/null": invalid format, then it proceeds to use the other keys you have configured anyway, and then fails to log in due to too many authentication failures.
    – Malvineous
    Feb 26, 2019 at 0:43
  • For me this didn't work. Maybe my credentials were stored in the gnome keyring.
    – Yaroslav Nikitenko
    May 13, 2019 at 11:49
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    This didn't work for me either. It found my id_rsa and used it. The ssh -o PubkeyAuthentication=no ... answer worked well.
    – bitinerant
    Feb 29, 2020 at 18:07

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