Configure Linux As Bastion Host

by

A bastion host is a server or virtual machine that is exposed to the public internet and is designed to act as a gateway to access other servers or resources in a private network. In this section, we will explain how to configure a Linux machine as a bastion host.

Here are the steps to configure a Linux machine as a bastion host:

  1. Choose a Linux machine that will act as a bastion host. This machine should be running a recent version of Linux and have a secure password policy in place.
  2. Disable root login and password authentication for SSH. This can be done by modifying the /etc/ssh/sshd_config file and setting the following parameters:
PermitRootLogin no
PasswordAuthentication no
  1. Configure SSH to listen on a non-standard port. By default, SSH listens on port 22, which is a common target for attackers. Changing the SSH port to a non-standard port can make it more difficult for attackers to find and target your server. To change the SSH port, edit the /etc/ssh/sshd_config file and modify the following line:
#Port 22
Port <your_new_port_number>
  1. Configure SSH access to the bastion host. Only authorized users should be able to access the bastion host. To configure access, you can add SSH keys for each user to the /home/<user>/.ssh/authorized_keys file. Alternatively, you can configure the bastion host to authenticate against a centralized authentication system, such as LDAP or Active Directory.
  2. Install a firewall on the bastion host. A firewall can help to restrict access to the bastion host and prevent unauthorized access to other resources on the private network. A good choice for a Linux bastion host is to use iptables, which is included in most Linux distributions.
  3. Configure a VPN to access private resources. To access private resources behind the bastion host, users should use a VPN connection. The VPN should be configured to authenticate against a centralized authentication system and should use a strong encryption protocol, such as OpenVPN or IPSec.
  4. Monitor and log all access to the bastion host. Monitoring access to the bastion host can help to detect and prevent unauthorized access to private resources. You can use tools such as logwatch or the ELK stack to collect and analyze logs.

That’s it! You have successfully configured a Linux machine as a bastion host. Remember to keep the bastion host up-to-date with the latest security patches and to follow security best practices to ensure the security of your private network.

Leave a Comment