After getting disconnected from the server (Ubuntu 18.04.1) I can not login anymore using public key.

I have 2 accounts that can run sudo. One account uses public key and a passphrase to login, and the other uses a password. Both accounts have existed for a long time and worked flawlessly. Now I have got a problem with the account that uses public key. When I try to login, i always get a question about passphrase, but that question is gone, and I get : "Permission denied (publickey)" without ssh asking for a passphrase. I have tried rebooting my client, but that does not help. I have rebooted my server and that does not help either. What helps, is if I use the other account (User2) that uses a password instead of a key and login to the server and disable the following rows in my sshd_config and and run "sudo service ssh restart":

#Match User User1
#PasswordAuthentication no

Then logout and run ssh user1@ Now I will be asked for a password and not a passphrase and then I will be logged in. If I then change the ssd_config back to

Match User User1
PasswordAuthentication no

and and run "sudo service ssh restart"

I will be able to use user1 to login and I will be prompted for a passphrase, so everything works.

This will work fine until the connection disconnects due to inactivity or i reboot my server (which will generate a disconnect). After that I have to repeat all steps above.

I have tried connecting from two different clients, one running Linux Mint and the other raspbian, the problem is the same.

I have also tried ssh -i .ssh/id_rsa user1@ and the result is the same "Permission denied (publickey)"

1 Answer 1


Your question is not clear but let me try to answer based on what I understood

You have 2 user... assuming ‘user1’ ‘user2’

If user1 needs to access user2 try copying the id_rsa.pub to user2 authorised_keys


cd .ssh
cat id_rsa.pub

Copy the key

Then login user2

cd .ssh
sudo nano authrized_keys

Paste the key you copied from id_rsa.pub

Then try connecting user2 from user1, you should be able to connect user2 without running into any issue

it should work...

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