Ubuntu – ssh permission denied(public key)

ssh

I have just installed VirtualBox and Vagrant on my coputer and initialized a ubuntu/bento-16.04 box. I have added a new user beside vagrant user and I have generated and copied the public key on the server in a file named authorized_keys. I also disbaled the possibility to authenticate with a paswword.

The problem is that i can connect to the server only if a provide to the ssh command the full path to my private key (located on the C drive of my computer), under -i flag.

If a try to connect just with ssh -p 2222 lucian@localhost i got this message:
permission denied(public key)

Is there any way i cann connect by ssh without providing the full path to the private key located on my computer?

My impression is that the server does not know about the location of the private key.

I red the earlier threads related to this issue but i can figure out what am I suppose to do to make the ssh-agent provide to the server the private key automatically.

Thanks!

Best Answer

Without editing files, you can use ssh-add yourkeyfile, it won't survive a reboot though.

To configure it as a permanent setting you can create or edit the following file

nano /home/yourusername/.ssh/config

Add the following entry

Host serverIP/FQDN
IdentityFile /home/yourusername/.ssh/yourkeyfile (or other path)

Now every time you connect to that specific host it will use that file.

You can also add the port number and username in the above configuration so that you only need to type ssh remotehostname to connect.

To do that add

 User remote_username
 Port remote_port#

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 Permission denied (public key), but root ssh works

SSH logins can fail for various reasons(incorrect directory/file permissions,incorrect keys etc.) and the connecting client will just get Permission denied or No more authentication methods to try or some generic error.
The exact reason for the login failure will be available in ssh log /var/log/auth.log or /var/log/secure depending on the syslog configuration.

Best Answer

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