Ubuntu – SSH user1@ip_address: Permission denied (publickey)

networkingpermissionsserverssh

I am trying to connect to a my SSH server (running on Ubuntu 16.04.2 LTS) from my local machine (Ubuntu 18.04.03 LTS).

I have created a private and public key on my local machine and copied my public key to my SSH server's authorized_keys file.

I could log in with ssh root@ip-address and I have access (as root user), but when I tried to log in as another user with command ssh name@ip-address, it generated an error message:

name@ip_address: Permission denied (publickey)

What can I do so the name@ip-address could be accessed?

Best Answer

Step 1: Open sshd_config file

sudo nano /etc/ssh/sshd_config

Step 2: Change the following lines

PermitRootLogin prohibit-password to PermitRootLogin yes 
PasswordAuthentication no to PasswordAuthentication yes

Step 3:restart ssh service:

sudo service ssh restart

PubKeyAuthentication

Set up your client

Generate your key.
```
ssh-keygen
```
Configure ssh to use the key.
```
vim ~/.ssh/config
```

Copy your key to your server.

ssh-copy-id -i /path/to/key.pub SERVERNAME`

Your config file from step 2 should have something similar to the following:

Host SERVERNAME
Hostname ip-or-domain-of-server
User USERNAME
PubKeyAuthentication yes
IdentityFile ./path/to/key

You can add IdentitiesOnly yes to ensure ssh uses the specified IdentityFile and no other keyfiles during authentication. Setting IdentitiesOnly prevents failed authentications from occurring, when ssh would otherwise attempt to login with multiple keys. Setting this is also considered more secure, as you're not leaking information about other keys you have installed, and maintaining separation of your keys between different levels of access.

Troubleshooting

use "-vvv" option
Make sure the server has your PUBLIC key (.pub).
Make sure your IdentiyFile points to your PRIVATE key.
Make sure your .ssh directory has 700 and the files within are 600 permissions.
- ssh-keygen will create files and directories for you with the proper permissions
tail -f /var/log/auth.log (on the server) and monitor errors when you attempt to login
If you have many key files, try IdentitiesOnly yes to limit the authentication to use the single, specified key.

Ubuntu – SSH login using Ubuntu’s terminal – Permission denied (publickey)

Check .ssh folder permission (run ls -laR ~/.ssh):

.ssh folder should have 700, while private key 600 and the public one can have 644.

Moreover, you can have more information about the problem running ssh with full debug logs

ssh -vvv ...

Best Answer

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