Bastion hosts have long been used to secure access to private servers, acting as a controlled gateway between users and sensitive resources. However, they come with certain limitations—manual configurations, operational overhead, and scaling challenges, to name a few. As infrastructure grows and compliance demands increase, the traditional bastion host model isn’t always the most effective solution.
Enter policy-as-code—a modern approach to enforce and verify granular access policies programmatically. When done right, it eliminates the single-point bottleneck of bastion hosts while enhancing security, flexibility, and scalability.
This post explores an alternative approach using policy-as-code instead of conventional bastion hosts.
Why Move Beyond Bastion Hosts?
Using bastion hosts once simplified secure environments. SSH access could be proxied through a central point, making it relatively straightforward to manage connections into private networks. Unfortunately, this model fails to scale effectively in dynamic cloud-native environments.
Common Pain Points with Bastion Hosts:
- Scaling Complexity: Additional administrative overhead arises as the number of environments, users, and servers grows.
- Lack of Fine-grained Policies: Permissions are often managed at coarse levels, making it harder to enforce least-privilege principles.
- Manual Configuration: Bastion hosts often require complex and error-prone manual setup and maintenance.
- Limited Audibility: Tracking who accessed what and when can become cumbersome. Centralizing logs is not always enough to ensure compliance.
Policy-as-code directly addresses these challenges by embedding security policies into infrastructure workflows, rather than relying on middleman servers or manual interventions.
What is Policy-As-Code?
Policy-as-code refers to writing, automating, and enforcing access control rules as code. These policies define what users, roles, or applications are allowed to do and operate as part of CI/CD pipelines or Infrastructure-as-Code (IaC) systems.
Instead of relying on hardware-like gates (e.g., bastion hosts), policy-as-code extends the zero-trust security model. Every action is verified against explicit, coded policies before being approved.
Key Features of Policy-As-Code:
- Programmatic Consistency: Policies behave predictably when written as code, reducing manual configuration errors.
- Version Control: Policies evolve alongside the codebase, with changes tracked securely using source control systems like Git.
- Dynamic Adjustments: As teams, environments, and workflows evolve, policies can be updated without making disruptive changes to infrastructure.
- Auditability: Programmed rules generate action logs automatically, simplifying compliance and ensuring traceability.
How Does Policy-As-Code Replace Bastion Hosts?
Traditional bastion hosts generally operate as a middle layer, verifying user identity and granting access to target systems. Replacing this with policy-as-code doesn’t just replicate functionality—it re-engineers how access and security are implemented.