What is a Bastion Host?

A bastion host is best defined as a server providing controlled access to external networks. It serves as a critical component in network security architecture, functioning as a gateway between an internal network and external, potentially untrusted networks such as the internet. A bastion host is typically hardened against attacks and is designed to withstand exploitation attempts, which allows it to manage and filter traffic between different network zones.

In practice, the primary purpose of a bastion host is to minimize the risk of exposure for the internal network. It acts as a focal point for access control, ensuring that any traffic entering or leaving the internal environment is monitored and scrutinized. The bastion host may host services such as firewalls, proxy servers, or VPNs, supporting secure communications with external networks while safeguarding sensitive internal resources.

Other potential choices present less accurate descriptions of a bastion host's purpose and functionality. For instance, while some network devices do provide services to end users or create connections to the internet, they do not necessarily embody the protective functions of a bastion host aimed specifically at ensuring controlled access to external networks. Additionally, backup systems focus on data recovery rather than managing network traffic securely, further distinguishing their roles from that of a bastion host.