You can add REMnux to an existing system based on Ubuntu 18.04 by following instructions below. This configuration doesn't modify your system's look and feel, so you won't have the experience of the full REMnux environment. To the full experience, consider using the REMnux virtual appliance.
After logging into your existing system based on Ubuntu 20.04 or 18.04, download the REMnux installer:
wget https://REMnux.org/remnux-cli
Validate that the SHA-256 hash of the downloaded file to make sure it matches this expected value:
8193df477c0e0f14b53d018db141b969ab48f8da550384ef6d6e51482ebdda9d
To generate the hash of your file, run:
sha256sum remnux-cli
Set up the REMnux installer by running these commands:
mv remnux-cli remnuxchmod +x remnuxsudo mv remnux /usr/local/bin
Before proceeding, make sure your system doesn't have an active Ubuntu unattended upgrade in progress. One way to do this is check whether the "unattended-upgrade" process is active (ps aux | grep unattended-upgrade.) If the upgrade is active, let it finish or disable it, then reboot the system before installing REMnux.
You're now ready to install the REMnux distro. To kick off the installation, run:
sudo remnux install --mode=addon
The addon mode will avoid modifications that can modify the look and feel of your existing system. As a result, you won't get the experience of the standard REMnux environment..
The installation will take about an hour, depending on your resources and internet connection.
If the REMnux installer produces an error, diagnose the issue by reviewing the saltstack.log file under /var/cache/remnux/cli in the subdirectory that matches the REMnux state-files version you're installing. Search for the log file for result: false messages and look at the surrounding 5 lines or the 8 lines above each message to see the state file that caused the issue. (grep -i -C 5 'result: false' or grep -i -B 8 'result: false').
Once the REMnux installation finishes, reboot your new REMnux system by typing:
sudo reboot
Login to your system to start benefiting from the tools that the REMnux distro includes.
To keep your REMnux environment up-to-date run the REMnux installer periodically as described in the Keep the Distro Up to Date section.
If you installed REMnux inside a virtual machine, consider taking a snapshot of the VM, so you can return it to a known good state if the need arises.