markpeek

Using certificates with SSH is the way to go for shared access servers. Here's an open source way (yes, I'm involved in the project) to manage authorization and access with asynchronous approvals:

https://github.com/cloudtools/ssh-cert-authority

Agreed on an SSH Certificate Authority being a good solution. Another open source project (disclaimer: I'm affiliated with it) which provides approval controls is available here: https://github.com/cloudtools/ssh-cert-authority