To encrypt a FreeBSD system using Geli (FreeBSD's disk encryption mechanism), follow these steps:
Prepare the FreeBSD Installation:
Start by booting into the FreeBSD installation media.
Proceed through the installation process until you reach the disk partitioning step.
Partition Your Disk:
Select the disk you want to install FreeBSD on.
Create partitions as needed. Typically, you'll want a separate partition for /boot and the rest for the root filesystem .
Encrypt the Partitions: