Bastion Host: Do you really need it?

There are several layers of security that you can put in place to protect your network from an external threat. One such security tool to use is a cloud business VPN, however, there are many other options available to cover different attack vectors. You may have read that a bastion host is a potential solution to your cybersecurity risks. However, bastion hosts are outdated technology and won’t be able to protect you against all attempted attacks. It is important to know what a bastion host is so that you can understand why alternative security methods are necessary.

What is a Bastion Host?

A bastion host is a specialized computer that is deliberately exposed on a public network. From a secured network perspective, it is the only node exposed to the outside world and is therefore very prone to attack. It is placed outside the firewall in single firewall systems or, if a system has two firewalls, it is often placed between the two firewalls or on the public side of a demilitarized zone (DMZ).

The bastion host processes and filters all incoming traffic and prevents malicious traffic from entering the network, acting much like a gateway. The most common examples are mail, domain name systems, Web, and File Transfer Protocol (FTP) servers. Firewalls and routers can also become bastion hosts.

How does it work?

To understand how a bastion host works, we will look at a simple scenario in which a company’s administrators need access to Linux instances connected on a subnet within a virtual private cloud. Exposing a port in each instance to the public internet would give administrators the access they need. But the security implications make that approach too risky.

Instead, it is used as a bridge between the public internet and the private subnet. The bastion runs as a locked-down, single-purpose system — in this case, an SSH proxy server. Administrators strip the bastion of all unnecessary applications, ports, processes, user accounts, and protocols. Everything that does not serve the bastion host’s single purpose as an SSH proxy gets disabled or deleted.

The bastion host resides on its own subnet with an IP address that is accessible from the public internet. The bastion only accepts SSH connections from a limited range of IP addresses in the IT department. ACLs, allowlists, and other network-level access controls limit access from the bastion to its protected subnets.

When authorized users need to access a resource on the private subnet, they must first use their SSH keys to establish a connection with the bastion host. Once authenticated, they can then use another set of SSH keys to connect with the private network.

Does your business need it?

You have sensitive information stored within your business. This data could be usernames and passwords, credit card numbers, customer details, and financial records.

As a business owner, you would not want anyone from outside your company to be able to access these private resources.

To prevent this from happening, a bastion host provides access to your employees but prevents hackers from gaining access to your information.

Some other reasons you may want to use a bastion host server within your business include:

• Secure remote access: Having remote teams makes your business far more vulnerable to attacks. Having a bastion host in place protects your private resources and allows employees to access your network remotely.
• Network segmentation: You can segment your private network, keeping it isolated from your external network.
• Logging and monitoring: You can monitor everyone who accesses your resources and keep track of everything that is happening within your network. This includes unsuccessful logins, which help you identify an attack.
• Single point of access: It creates a single point of access that makes it easier to control who accesses your business resources. This can prevent attackers from gaining access to your entire network once they have penetrated one system.
• Hardening: Usually, they are hardened. This means they are secured against some of the more common attacks, making it difficult for attackers to access your network.

What is the difference between a firewall and a bastion host

Firewalls and bastion hosts are both security tools, but they serve distinct purposes:

A firewall acts as a wall, blocking unauthorized traffic based on predetermined rules. It’s like the castle gatekeeper who decides who enters based on a set of criteria.

Bastion Host provides controlled access for authorized users through secure channels.

While firewalls block unwanted traffic, bastion hosts enable secure access for authorized users. They work together to create a layered defense system for your network.

What is the difference between a VPN and a bastion host

Both of them enable secure remote access, but their approaches differ:

A VPN creates a secure tunnel between a remote device and the internal network, encrypting all traffic passing through it. It’s like a secret passageway, allowing authorized users to access the entire network directly.

A bastion host acts as a centralized gateway, controlling and monitoring all remote access through a single point. It’s like a secure checkpoint for verified users before granting access to specific resources within the network.

What are the security risks of using a Bastion Host?

Like any other technology application, bastion hosts expose organizations to security risks. These risks stem from the fact that bastion hosts provide internal access through the Secure Shell Protocol (SSH) protocol. SSH is an encryption and authentication method widely used in communications between networks.

Cyber attackers often target it since gaining access to the SSH encryption keys can give them high-level access to the protected network. It’s like giving thieves a master key that can open any room in a house. Once attackers have the SSH key, they can bypass the bastion host and access the internal network.

Another risk bastion hosts pose is that they are publicly visible. As such, attackers may find it easy to obtain access through brute-force attacks where they use trial and error to guess passwords or SSH keys.

Conclusion

Some say using bastion hosts and jump servers is obsolete. In small IT infrastructures, if you configure them right and harden security, they are a fair solution for their role. But you should remember that a bastion host can only do one trick. Work as a gateway between an external and an internal network. That’s all.

Depending on your company’s specific needs, resources, and skills, a bastion host can do a good job protecting access to your private network. You’ll need to manage it with extra care and keep a keen eye on patching, vulnerability scanning, and so on.