Blocklist of all Facebook domains
Not the way I'd do it, since you can easily miss on some new domain that belongs to facebook (or perhaps some server that does not look like it belongs to facebook in the first place, but it is sitting in their assigned subnets).If you really want to block all traffic from/to facebook, lookup the IP prefixes associated with their AS number(AS32934), and setup your firewall to block those. If you are using PF, tables are your friend. With netfilter, consider using ipset.