Configure Debian 12 Bastion Server

I need a bastion server set up on Debian 12. Its main role will be centralized access management. The server will primarily manage SSH connections, and I require it to use public key-based authentication exclusively.

Key tasks:
- Set up the bastion server on Debian 12
- Configure it for centralized management of SSH access
- Implement public key-based authentication

Ideal skills for this job include:
- Extensive experience with Debian 12
- Proficiency in configuring bastion servers
- Expertise in SSH and public key-based authentication
- Previous experience in centralized access management