Securing Remote Access: How to Configure a Jump Host (Bastion) for Admin Access

Administrative access is one of the most critical attack vectors in any IT environment. Exposing admin interfaces directly to the internet creates massive risk, from brute-force attacks to credential theft.

The solution? A jump host—also known as a bastion host.

A jump host acts as a controlled gateway between administrators and critical infrastructure, providing a single hardened point of entry that enforces authentication, monitoring, and auditing.

In this article, we’ll cover:

• What a jump host is and why it’s essential
• Security benefits of using a bastion host
• Step-by-step configuration guidance
• Best practices for securing your bastion environment

What Is a Jump Host (Bastion)?

A jump host is a dedicated server placed in a demilitarized zone (DMZ) or restricted subnet that admins must log into before accessing sensitive internal systems.

Instead of connecting directly to production servers, admins connect through the bastion, which:

• Authenticates users
• Provides logging and auditing
• Restricts access pathways
• Acts as a choke point for admin activity

Benefits of Using a Bastion Host

• Centralized Access Control – One gateway to manage admin access
• Improved Security – Reduces the attack surface of production servers
• Auditing & Compliance – Logs all administrative sessions
• Separation of Duties – Enforces least-privilege and access segmentation
• Reduced Lateral Movement Risk – Limits the ability of attackers to pivot inside the network

Step 1: Deploy the Jump Host

• Place the jump host in a secure subnet (e.g., a DMZ or management VLAN).
• Use a minimal, hardened operating system (e.g., Ubuntu Server, RHEL, or Windows Server Core).
• Ensure only required services (e.g., SSH or RDP) are running.

Step 2: Configure Network Access

• Restrict inbound access to the jump host from trusted IP addresses only (e.g., corporate VPN).
• Allow outbound access only to the servers that require administrative access.
• Use firewalls and network security groups (NSGs) to enforce strict segmentation.

Step 3: Set Up Authentication

• SSH (Linux Jump Host):
  • Disable password authentication; use SSH key pairs.
  • Configure sshd_config to enforce strong ciphers and protocols.
  Example settings in /etc/ssh/sshd_config: PermitRootLogin no PasswordAuthentication no AllowUsers adminuser
• RDP (Windows Jump Host):
  • Enforce Network Level Authentication (NLA).
  • Require multi-factor authentication (MFA).
• Integrate authentication with Active Directory (AD) or another centralized identity provider.

Step 4: Enforce Multi-Factor Authentication (MFA)

• Require MFA before accessing the bastion.
• Solutions include Azure MFA, Duo, Okta, or hardware tokens.

Step 5: Configure Session Logging & Monitoring

• Enable detailed logs of all login attempts and session activity.
• Use centralized logging (e.g., syslog, SIEM, or Windows Event Forwarding).
• For high-security environments, implement session recording for auditing.

Step 6: Limit Privileges

• Apply the principle of least privilege:
  • Only admin users should access the bastion.
  • Use role-based access to restrict commands or destinations.
• Separate jump accounts from normal user accounts.

Step 7: Maintain and Harden the Jump Host

• Regularly patch and update the bastion OS.
• Disable unnecessary ports and services.
• Install endpoint protection (anti-malware, intrusion detection).
• Restrict copy/paste and file transfers unless explicitly required.

Best Practices for Bastion Hosts

• Deploy Redundancy – Have at least two bastion hosts for high availability.
• Use Short-Lived Credentials – Issue temporary credentials for admins.
• Monitor in Real Time – Use security tools to detect unusual activity.
• Audit Frequently – Review logs and session data to detect policy violations.
• Cloud Environments – Use managed bastion services (e.g., Azure Bastion, AWS Systems Manager Session Manager) when available.

Conclusion

Configuring a jump host (bastion) is one of the best ways to secure administrative access to critical infrastructure. By enforcing centralized authentication, MFA, logging, and least privilege, you significantly reduce the risk of unauthorized access and lateral movement within your network.

Whether in on-premises or cloud environments, a bastion host should be a core component of your Zero Trust security strategy.