This question was inspired by this thread
The hypothetical scenario, for context is as follows:
- SSH servers, whether they be routers, firewalls etc. are all firstly provisioned within a private + secure environment before being deployed. The SSH keys are generated locally on the server in this environment.
- The SSH servers have their own ACLs in place for refusing connections from anything but our hosts
- The host machine will be a Linux machine with multiple users
The standard approach may be to employ PKI with a trusted CA installed on all user accounts, and deploy a local SCEP server etc. But in place of this, would it be prudent to:
While in the secure environment, and upon provisioning, import the RSA fingerprint of the server to the
known_hostscontainer of our host machine (or wherever it would be stored, I'm not overly familiar with Linux yet) using
ssh-keyscan -H x.x.x.x >> ~/.ssh/known_hosts
Share/mirror that container of RSA fingerprints across the users on that host machine
Configure the host/each user to reject/drop/refuse the connection when given the following prompt, so that
The authenticity of host '[hostname] ([IP address])' can't be established. RSA key fingerprint is [key fingerprint]. Are you sure you want to continue connecting (yes/no)?
- They cannot connect to any server that hasn't gone through this procedure, then
- Perhaps create a sandboxed separate user for cases where these aforementioned processes + restrictions cannot be implemented, but where remote configuration is still needed, so that the main more commonly-used passwords are not compromised by a possibly fake SSH server.