The standard OpenSSH suite of tools contains the ssh-keygen utility, which is used to generate key pairs. Run it on your local computer to generate a 2048-bit RSA key pair, which is fine for most uses. Ssh-keygen The utility prompts you to select a location for the keys.
- Command To Generate Old Openssh Format Key On Mac
- Openssh Key Format
- Openssh Generate Public Key From Private Key
[donotprint][/donotprint]To regenerate keys you need to delete old files and reconfigure openssh-server. It is also safe to run following commands over remote ssh based session. Your existing session shouldn’t be interrupted.
Advertisements
Why regenerate new ssh server keys?
Most Linux and Unix distribution create ssh keys for you during the installation of the OpenSSH server package. But it may be useful to be able re-generate new server keys from time to time. For example, when you duplicate VM (KVM or container) which contains an installed ssh package and you need to use different keys from cloned KVM VM guest/machine.
Steps to regenerate OpenSSH host keys on Linux
Let us see all steps
Command To Generate Old Openssh Format Key On Mac
Step 1 – Delete old ssh host keys
Openssh Key Format
Login as the root and type the following command to delete files on your SSHD server:
Sample outputs:
# /bin/rm -v /etc/ssh/ssh_host_*
Sample outputs:
Step 2 – Debian or Ubuntu Linux Regenerate OpenSSH Host Keys
Now create a new set of keys on your SSHD server, enter:
Sample output:
# dpkg-reconfigure openssh-server
Sample output:
You just regenerated new ssh server keys. You need to restart ssh server:
OR
$ sudo systemctl restart ssh
OR
$ /etc/init.d/ssh restart
Step 3 – Update all ssh client(s) known_hosts files
Finally, you need to update ~/.ssh/known_hosts files on client computers, otherwise everyone will see an error message that read as follows:
Either remove host fingerprint or update the file using vi text editor (command must be typed on client machine):
Now login using the ssh command:
$ ssh-keygen -R remote-server-name-here
Now login using the ssh command:
$ ssh [email protected]
Conclusion
Openssh Generate Public Key From Private Key
You just regenerated OpenSSH Host Keys on a Debian or Ubuntu Linux using the dpkg-reconfigure command. For more info see the man page or this wiki page here:
$ man dpkg-reconfigure
$ man sshd
ADVERTISEMENTS