Tuesday, January 19, 2021

FreeBSD, the alternative

 I like FreeBSD. Something about a barebones, simple UNIX that is clean at the core. Not particularly a pragmatic choice, I'll gladly admit. For most needs, a Linux installation is both simpler and more capable. More people are familiar with Linux, so this is a niche world.

But FreeBSD is a hobby, and a particularly gratifying hobby.

The simplicity of FreeBSD is a huge draw, you can get very far with an ancient Intel machine and 1 GB of RAM. The source code is a pleasure to read, the system is easy to modify, and there is relatively little of it on a base install. Full system upgrades are clean and easy, the ports system is elegant though often impractical.

For most people, the easiest way to run FreeBSD would be to use a virtual image, and boot it up using qemu (Linux) or Hyper-V (Windows). Both work very well, both support networking, which is really what you're looking for. Face it, you're not booting into FreeBSD for its giant catalog of games or media utilities.

Get the VM images from here. qcow2 works for QEMU, vhd works for Hyper-V, and vmdk works for VMWare. 

For QEMU, I use the following commandline:

qemu-system-x86_64 \
        -m 2048 \
        -enable-kvm \
        -hda bsd-with-jail.img \
        -net user,hostfwd=tcp::10023-:22 \
        -net nic \

That specifies:

  • (-m 2048) 2048 MB RAM
  • (-enable-kvm) use the Linux KVM hypervisor
  • (-hda bsd-with-jail.img) the disk bsd-with-jail.img as the first hard disk 
  • (-net nic)  a full Network Interface Card, make your FreeBSD setup trivial as it can get a network interface called em0
  • (-net user, hostfwd=tcp::10023-:22) network translation is user-level, so no root permissions required and forward port 10023 on the host to port 22 on the guest. This allows you to ssh to the FreeBSD guest by ssh'ing port 10023 on the host.
  • (-curses) Use the text-based interface using libncurses rather than a graphical interface. Great for running on cloud instances, or through GNU screen so you can leave it on forever.

Other ports can be forwarded for running web servers, dns servers, ...

The same setup can be replicated on Hyper-V. For network, you can use the default switch. Port forwarding is more complicated, and you could achieve it with ssh tunnels on the Windows host or in the FreeBSD guest.

FreeBSD runs fine with 1GB of RAM, and is a great system to learn the fundamentals of computing. You can play with Dtrace, create constrained environments called Jails, or modify the behavior of a clean UNIX kernel.  A lot of this knowledge translates to Mac OS, as the OS X kernel is a hybrid of FreeBSD and Mach, and the userland is very similar to FreeBSD.

You can easily run a dozen jails on 1G of RAM, depending on what you do with them.  Each jail is separated from the other and can be a low-cost, throwaway computing environment. Similar to Docker, or Linux namespaces, root in a jail is safe, and cannot damage the host FreeBSD system.

Set up your own UNIX sandbox today!