[SOLVED] VMs have identical ssh_host_rsa_id keys?

scottieH · 04-21-2021, 04:47 PM

I'm doing some testing, and I have 2 VMs setup to do so. I've noticed that these 2 machine have identical /etc/ssh/ssh_host_rsa_id keys.

Is this expected? Is it related to the hypervisor? They were instantiated from a the same image?

~Confused in Colorado

Im Runnin RHEL 7.9 with openSSH 4.44

rknichols · 04-21-2021, 06:08 PM

New ssh server keys are auto-created only if they do not already exist. If the base image contains the /etc/ssh/ssh_host* files, then each VM instantiated from that image will simply use those key files.

scottieH · 04-21-2021, 07:07 PM

Quote:

Originally Posted by rknichols

New ssh server keys are auto-created only if they do not already exist. If the base image contains the /etc/ssh/ssh_host* files, then each VM instantiated from that image will simply use those key files.

So, I shou8ld be able to re-build them without issue? Do I need to restart sshd or anything?

rknichols · 04-21-2021, 10:32 PM

Yes, you can rebuild the key files. As for restarting sshd, I have no idea, but it's a simple thing to do, so why not? Actually, the simplest thing to do would be to delete the existing files and then restart sshd, which will auto-create new key files.

Turbocapitalist · 04-22-2021, 01:43 AM

The ssh-keygen utility has the -A option for generating the host keys, but I would say the above recommendation of deleting the host keys and restarting the SSH daemon will be easier.

scottieH · 04-22-2021, 04:55 PM

Quote:

Originally Posted by Turbocapitalist

The ssh-keygen utility has the -A option for generating the host keys, but I would say the above recommendation of deleting the host keys and restarting the SSH daemon will be easier.

Didn't even need to restart sshd. Thanks!