Bastion Host

ELI5 — The Vibe Check

A bastion host is a hardened server that acts as the only entry point into your private network. Want to SSH into a private instance? You SSH into the bastion first, then jump to the private instance. It's like a security checkpoint — everyone has to pass through this one door. Also called a 'jump box' because you jump through it.

Real Talk

A bastion host (jump box) is a special-purpose instance deployed in a public subnet to provide secure access to instances in private subnets. It's hardened with minimal software, restricted access (IP whitelist, SSH key auth), and full audit logging. Modern alternatives include AWS Systems Manager Session Manager, which eliminates the need for bastion hosts entirely.

When You'll Hear This

"SSH to the bastion, then jump to the private instance from there." / "We replaced our bastion host with Systems Manager Session Manager — no more managing that instance."