What is a bastion host?

A network is a critical component of any organization’s infrastructure, facilitating communication, data transfer, and resource sharing. However, the rise in cyber threats highlights the need for robust network security measures to protect sensitive information and systems from unauthorized access. One such measure is the use of a bastion host.

Understanding bastion host

A bastion host (also known as jump box) is a highly secure server specially designed to act as a fortified gateway between public and private networks.

The primary purpose of a bastion host is to enhance network security by providing controlled access to authorized users while mitigating the risk of potential threats. It ensures that the protected services have no direct access to the public internet. Below are some common examples of bastion hosts that can be seen in the real world.

Let’s take a real-world example to understand the workings of a bastion host.

Working of a bastion host

Let’s assume we are running a web application that consists of a web server and a database server. We have a firewall in place to allow users to access only the web server. We also have our admin who can access both web and database servers to perform its tasks. This filtration can be performed based on the admin IP address or some other criteria. This scenario is demonstrated in the illustration below:

Let’s say that the admin is using SSH protocol to access the web and database servers. For this, we might have to open port 22 on the firewall. Opening unnecessary ports to the public internet without authentication and authorization can have serious consequences.

To solve this problem, a bastion host is deployed and the request coming from the bastion host, after successful authentication and authorization, is allowed to access the internal services. The below illustration shows the communication flow after adding the bastion host to the scenario.

The bastion host is designed to be a single point of entry for authorized users, ensuring that all network traffic passes through it. This allows for centralized monitoring and control of incoming connections.

Benefits of using a bastion host

Incorporating a bastion host into a network infrastructure brings numerous benefits to network security:

• Fortified defense: It serves as a formidable barrier against unauthorized access attempts, effectively minimizing the attack surface. By requiring users to authenticate and establish a connection through the bastion host, the risk of external threats breaching the internal network is significantly reduced.

• Enhanced security: A bastion host often includes additional security measures, such as intrusion detection and prevention systems, firewalls, and access control mechanisms. These features help protect against unauthorized access attempts, malicious activities, and potential exploits.

• Active maintenance: The bastion hosts are frequently updated with security patches to minimize potential attack risks. They also regularly undergo security audits and forensic analysis to detect anomalous behavior or suspicious activity, allowing for timely responses and threat mitigation.

Conclusively, bastion hosts provide robust security measures, including strict access control and ongoing threat protection against potential threats.

Best practices

When deploying a bastion host, it’s essential to follow established best practices to ensure optimal security and functionality:

• Isolation: The bastion host should be physically and logically isolated from both the external and internal networks.

• Authentication: A strong authentication mechanism, such as multi-factor authentication, should be implemented to verify user identities.

• Authorization: Care must be taken when defining access control policies for the bastion host, and the access should be granted on a need-to-know basis.

• Disable services: When configuring a bastion host, a minimalistic approach should be followed, and all unnecessary services must be removed to reduce the attack surface.

• Security updates: Review and update the software and firmware regularly and apply security patches promptly to adhere to industry best practices and security standards.

Conclusion

Bastion hosts play a critical role in network security for various organizations, including financial institutions and government agencies. Serving as controlled entry points, they monitor activity and enforce access controls, enhancing security and protecting sensitive data from cyber threats. Integrating bastion hosts into network infrastructure is the best practice for maintaining robust security defenses against evolving digital threats.