Block and unblock all Facebook IP addresses on macOS (using pfctl, so it might work on BSD as well)

block-facebook.sh

#!/bin/bash

( \
  echo -n "table <facebook> persist { "; \
  whois -h whois.radb.net '!gAS32934' | tail -n 2 | head -n 1 | sed 's/\ /,\ /g' | tr -d '\n'; \
  echo -n ', '; \
  whois -h whois.radb.net '!6AS32934' | tail -n 2 | head -n 1 | sed 's/\ /, /g' | tr -d '\n'; \
  echo ' }'; \
  echo "block quick to <facebook>" \
) | sudo pfctl -f -
sudo pfctl -E

unblock-facebook.sh

#!/bin/bash

sudo pfctl -t facebook -T kill
sudo pfctl -F rules

This script looks up all IPv4 and IPv6 ranges in use by Facebook, adds them to a PF table and blocks traffic to addresses in that table. Unblocking is done by removing the table and flushing all rules, so use at your own discretion, should you have other PF rules in place!