SSH: Linux Generate Public/Private Key Login

[Tor]

On your desktop or the computer you want to SSH from run this command:

# ssh-keygen -t dsa

• You will be asked to enter a location, use the default.
• Enter a prassphrase (it is not recommended to leave this blank)

You will see results similar to this:

Your identification has been saved in /home/username/.ssh/id_dsa.
Your public key has been saved in /home/username/.ssh/id_dsa.pub.
The key fingerprint is:
6b:62:7c:60:81:04:97:3e:62:c8:1c:9e:96:49:11:b4 name@host

Now you need to put your public key on the remote server in a file at ~/.ssh/authorized_keys2. You can do this one of two ways.

1) Execute this command:

# cat ~/.ssh/id_dsa.pub | ssh username@hostname 'cat - >> ~/.ssh/authorized_keys2'

2) Copy/Paste the file.

• Open ~/.ssh/id_dsa.pub using vi/vim/nana/pico/etc (your favorite editor).
• Select all of the contents and copy the data into your clipboard.
• SSH into the remote server
• vi/vim/nano/pico/etc (your favorite editor) ~/.ssh/authorized_keys2
• Paste the contents of your clipboard (should be the public key copied from above).
• Save the file

That is it! Logout of the remote system and then SSH back into the remote system. If everything worked fine you should be asked for a passphrase.

[Jordan]

Thanks Tor, this will be helpful. I'm constantly looking this information up as well.

[phpforfun]

Tor, I am looking into doing this, do you mind explaining how to reverse the process? Say you wanted to remove a key. Do you delete the key files, or clear them out?

[Jordan]

If you want to remove a single key just remove it from this file:~/.ssh/authorized_keys2
It is easy to see how they are segmented and delete only one. Alternatively you can delete the whole file to remove all keys.