Basic Installation

If you are just upgrading from a previous version, please read upgrading instead.

0. Got Puppet?

We published a Puppet module to handle The Bastion configuration and prerequisites. The GitHub repo is here and our module has been published to the Puppet forge. Of course, its usage is completely optional, but if you choose to use it, some of the below steps will be done by Puppet. Hence, you might want to only consider the following steps:

1. Operating system

Warning

The Bastion expects to be the only main service running on the server, please see this FAQ entry for more information.

The following Linux distros are tested with each release, but as this is a security product, you are warmly advised to run it on the latest up-to-date stable version of your favorite OS:

  • Debian 11 (Bullseye), Debian 10 (Buster), 9 (Stretch)
  • CentOS 7.x
  • RockyLinux 8.x
  • Ubuntu LTS 22.04, 20.04, 18.04, 16.04
  • OpenSUSE Leap 15.3*

*: Note that these versions have no out-of-the-box MFA support, as they lack packaged versions of pamtester, pam-google-authenticator, or both. Of course, you may compile those yourself. Any other so-called modern Linux version are not tested with each release, but should work with no or minor adjustments.

The following OS are also tested with each release:

  • FreeBSD/HardenedBSD 13.0**

**: Note that these have partial MFA support, due to their reduced set of available pam plugins. Support for either an additional password or TOTP factor can be configured, but not both at the same time. The code is actually known to work on FreeBSD/HardenedBSD 10+, but it's only regularly tested under 13.0.

Other BSD variants, such as OpenBSD and NetBSD, are unsupported as they have a severe limitation over the maximum number of supplementary groups, causing problems for group membership and restricted commands checks, as well as no filesystem-level ACL support and missing PAM support (hence no MFA).

In any case, you are expected to install this on a properly secured machine (including, but not limited to: iptables/pf, reduced-set of installed software and daemons, general system hardening, etc.). If you use Debian, following the CIS Hardening guidelines is a good start. We have a tool to check for compliance against these guidelines. If you use Debian and don't yet have your own hardened template, this script should help you getting up to speed, and ensuring your hardened host stays hardened over time, through a daily audit you might want to setup through cron.

Great care has been taken to write secure, tested code, but of course this is worthless if your machine is a hacker highway. Ensuring that all the layers below the bastion code (the operating system and the hardware it's running on) is your job.

2. Connect to your server as root

You'll need to be connected to your server as root to perform the installation. If you're using root password authentication through SSH to do so, note that during the installation, as the SSH server configuration will be hardened, the SSH password authentication will be disabled server-wide.

Hence, to access your server, please set up an SSH public key authentication instead of a password authentication, and do so before proceeding with the next steps. Otherwise you might lose access to your own server once the SSH hardening will be in effect, as password authentication will then be disabled.

3. Get the code

The bastion code usually lives under /opt/bastion. You can either use git clone directly, or get the tarball of the latest release.

  • Using git:
git clone https://github.com/ovh/the-bastion /opt/bastion
git -C /opt/bastion checkout $(git -C /opt/bastion tag | tail -1)
  • Using the tarball:

Get the tarball of the latest release, which can be found there, then untar it:

mkdir -p /opt/bastion
tar -C /opt/bastion -zxf v3.09.02.tar.gz

The code supports being hosted somewhere else on the filesystem hierarchy, but this is discouraged as you might need to adjust a lot of configuration files (notably sudoers.d, cron.d, init.d) that needs an absolute path. You should end up with directories such as bin, lib, etc. directly under /opt/bastion.

4. Install the needed packages

For the supported Linux distros (see above), you can simply run:

/opt/bastion/bin/admin/packages-check.sh -i

You can add other parameters to install optional packages, depending on your environment:

  • -s to install syslog-ng (advised, we have templates files for it)
  • -d to install packages needed for developing the software (useless in production)

You'll also need our version of ttyrec, ovh-ttyrec. To get and install the precompiled binary that will work for your OS and architecture, you can use this script:

/opt/bastion/bin/admin/install-ttyrec.sh -a

This will detect your distro, then download and either install the .deb or .rpm package for ovh-ttyrec. If your distro doesn't handle those package types, it'll fallback to installing precompiled static binaries. Of course you can package it yourself and make it available to your own internal repositories instead of installing it this way.

If you plan to use the PIV functionalities of The Bastion, you'll also need to install the yubico-piv-checker helper tool:

/opt/bastion/bin/admin/install-yubico-piv-checker.sh -a

5. Encrypt /home

Strictly speaking, this step is optional, but if you skip it, know that all the SSH private keys and session recordings will be stored unencrypted on the /home partition. Of course, if partition encryption is already handled by the OS template you use, or if the storage layer of your OS is encrypted by some other mean, you may skip this section.

First, generate a secure password on your desk (but not too complicated so it can be typed on a console over your hypervisor over a VDI over VPN over 4G in the dark at 3am on a Sunday) and save it to a secure location: pwgen -s 10.

Then you can use the helper script to do this, it'll guide you through the process. When prompted for a passphrase, enter the one chosen just before:

/opt/bastion/bin/admin/setup-encryption.sh

If you get a cryptsetup error, you might need to add --type luks1 to the cryptsetup luksFormat command in the script. It can happen if your kernel doesn't have the necessary features enabled for LUKS2.

Warning

Once you have setup encryption, do not forget to ensure that the keys backup script has encryption enabled, otherwise the backups will be stored unencrypted in /root/backups, which would make your /home encryption moot. This is not covered here because you can do it later, just don't forget it: it's in the advanced installation section.

6. Setup bastion and system configuration

The following script will do that for you. There are several possibilities here.

  • If you're installing a new machine (nobody is using it as a bastion yet), then you can regenerate brand new host keys and directly harden the ssh configuration without any side effect:
/opt/bastion/bin/admin/install --new-install
  • If you're upgrading an existing machine (from a previous version of this software), and there are already some people using it as a bastion, then if you change the host keys, they'll have to acknowledge the change when connecting, i.e. this is not transparent at all. To avoid doing that and not touching either the ssh config or the host keys, use this:
/opt/bastion/bin/admin/install --upgrade

If you used --upgrade, then you are warmly advised to harden the configuration yourself, using our templates as a basis. For example, if you're under Debian 11:

vimdiff /opt/bastion/etc/ssh/ssh_config.debian11 /etc/ssh/ssh_config
vimdiff /opt/bastion/etc/ssh/sshd_config.debian11 /etc/ssh/sshd_config

There are other templates available in the same directory, for the other supported distros.

  • If you want to have a fine-grained control of what is managed by the installation script, and what is managed by yourself (or any configuration automation system you may have), you can review all the fine-grained options:
/opt/bastion/bin/admin/install --help

7. Review the configuration

Base configuration files have been copied, you should review the main configuration and modify it to your needs:

vim /etc/bastion/bastion.conf

8. Check that the code works on your machine

This script will verify that all required modules are installed:

/opt/bastion/bin/dev/perl-check.sh

9. Manually create our first bastion account

Just launch this script, replacing USERNAME by the username you want to use:

/opt/bastion/bin/admin/setup-first-admin-account.sh USERNAME auto

You'll just need to specify the public SSH key to add to this new account. It'll be created as a bastion admin, and all the restricted commands will be granted.

Note

This command will also give you a so-called bastion alias, this is the command you'll routinely use to connect to the bastion, and to your infrastructures through it, replacing in effect your previous usage of the ssh command. The alias name advertised on account creation is configurable in bastion.conf, and of course the users can rename it as they see fit, but it's advised to keep this command short, as people will use it a lot.

If you want to create other admin accounts, you can repeat the operation. All the other accounts should be created by a bastion admin (or more precisely, by somebody granted to the accountCreate command), using the bastion own commands. But more about this in the section Using the bastion.

Now that your bastion is installed, you can either check the advanced installation documentation, or head over to the USAGE section on the left menu.