This guide is for FreeBSD 10.1-RELEASE. It should work, with slight modifications, for all other relatively modern versions.
Make sure you are up to date, by running:
freebsd-update fetch freebsd-update install
pkg install redis
Follow the regular steps to run Redis at the runlevel, and start it.
pkg install gcc5
pkg install node
Clone NodeBB repo (this assumes you have git installed, otherwise use pkg to install it):
git clone -b v2.x https://github.com/NodeBB/NodeBB.git
Run interactive installation:
You may leave all of the options as default.
You are finished! After the installation, run:
Visit your forum at
http://FQDN:4567/ to finish configuration and
setup. FQDN is the server fully qualified domain name.