bastionhost

A bastion host, also known as a jump server, is a hardened computer positioned at the edge of a network to serve as the controlled entry point for administrative access to systems inside a protected network. It is typically placed in a DMZ or public subnet and is minimized to reduce exposure.

Administrators connect to the bastion using secure protocols such as SSH or RDP, often with multi-factor authentication. From the bastion, they then access internal hosts, usually through SSH or management tools, sometimes using port forwarding or session recording. This model centralizes access and improves auditability while limiting direct exposure of internal systems.

Key deployment considerations include strong hardening, regular updates, strict access controls, and comprehensive logging. Often a bastion is configured with only essential services; multiple bastions may be deployed for reliability, and access is restricted by IP allowlists or identity-based controls. High availability and continuous monitoring are commonly implemented.

In cloud environments, bastion functionality may be provided by dedicated services or by jump hosts within public subnets. Some platforms offer managed session managers that allow administrators to connect to internal resources without exposing direct endpoints.

A bastion host is not a firewall or VPN gateway; rather it is a controlled entry point intended for management traffic. It should be one of the most secure components in an operational security architecture, with clear ownership, lifecycle management, and periodic security reviews.