There is always the option to send it via syslog, but it would be easier just using the beats to parse and send logs to a centralized logging platform. in this case a Hot-Warm elastic search cluster fronted by two Logstash machines (definitely overkill though).

Initial Setup

So for this task i'll be using Vagrant in order to simple have a VM that i can build the beats from the git source.

Best way to install with current instructions is using the official Vagrant Installation Guide.

I'll be also using Virtual box as a provider.

Vagrantfile

Vagrant deploys virtual machines by a Vagrant File specification. We are compiling to a FreeBSD 11.2 system which means that we'll also specify for vagrant to spin up such a box.

My Vagrant file looks like following, now you can certainly put it somewhere else, bu i just need the FreeBSD machine for this purpose, and will be destroyed after this compile hence putting it into /tmp.

root@ubuntu:~# mkdir freebsd-compile
root@ubuntu:~# cd freebsd-compile/^C
root@ubuntu:~# mkdir -p /tmp/freebsd-compile
root@ubuntu:~# cd /tmp/freebsd-compile/
root@ubuntu:/tmp/freebsd-compile# cat <<EOF > Vagrantfile
> Vagrant.configure("2") do |config|
> config.vm.box = "freebsd/FreeBSD-11.2-RELEASE"
> config.vm.box_version = "2018.06.22"
> end
> EOF
root@Valkyrie:/tmp/freebsd-compile# cat Vagrantfile
Vagrant.configure("2") do |config|
  config.vm.box = "freebsd/FreeBSD-11.2-RELEASE"
  config.vm.box_version = "2018.06.22"
end
root@Valkyrie:/tmp/freebsd-compile#

Good now that's all we need for our host system, lets start up the VM by using vagrant up in the vagrant file directory and wait.

root@ubuntu:/tmp/freebsd-compile# vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Importing base box 'freebsd/FreeBSD-11.2-RELEASE'...
==> default: Generating MAC address for NAT networking...
==> default: Checking if box 'freebsd/FreeBSD-11.2-RELEASE' version '2018.06.22' is up to date...
[... snip ...]

Now for me it did toss some errors trying to remote connect, but fear not. The machine is provisioned and started and we can now connect to it using vagrant ssh.

root@Valkyrie:/tmp/freebsd-compile# vagrant ssh
FreeBSD 11.2-RELEASE-p14 (GENERIC) #0: Mon Aug 19 22:38:50 UTC 2019

Welcome to FreeBSD!
[... snip ...]
vagrant@freebsd:~ % sudo su
root@freebsd:/home/vagrant # cd
root@freebsd:~ #

Now comes the compiling of beats. And for this chapter i actually want to give a very large kudos to Jakommo who came up with it, but its too good not to have it drown in a github issue.

Package installation and Compilation

Now in order to succeed, we need a couple of packages installed into our VM.

root@freebsd:~ # pkg install git gmake go bash
Updating FreeBSD repository catalogue...
FreeBSD repository is up to date.
All repositories are up to date.
The following 25 package(s) will be affected (of 0 checked):

New packages to be INSTALLED:
    git: 2.23.0
    [... snip ...]
    cvsps: 2.1_2

Number of packages to be installed: 25
Proceed with this action? [y/N]: y

root@freebsd:~ #

Now we have all the dependencies in order to compile, lets get the code and checkout the correct version. (I deliberately removed a lot of the output as that is of no importance if it throws no errors)

root@freebsd:~ # go get github.com/elastic/beats
root@freebsd:~ # cd src/github.com/elastic/beats/
root@freebsd:~/src/github.com/elastic/beats # git checkout v7.5.0
Note: switching to 'v7.5.0'.
root@freebsd:~/src/github.com/elastic/beats # cd /filebeat
root@freebsd:~/src/github.com/elastic/beats/filebeat # gmake
root@freebsd:~/src/github.com/elastic/beats/filebeat # file filebeat
filebeat: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD)...
root@freebsd:~/src/github.com/elastic/beats/filebeat # ./filebeat version
filebeat version 7.5.0 (amd64), libbeat 7.5.0 ....
root@freebsd:~/src/github.com/elastic/beats/metricbeat # ./metricbeat version
metricbeat version 7.5.0 (amd64), libbeat 7.5.0 ....
root@freebsd:~/src/github.com/elastic/beats/metricbeat #

Now its just a matter of copy the filebeat binary to your pfsense and configure it according to the beats documentation.

Note: This also work for auditbeat, packetbeat and metricbeat. but would be a redundant wall of text showing all 4 binaries.

Again all credit goes to Jakommo for writing the comment on Github.