I haven't looked in a while, but an update would be nice. When I was looking at it in the last couple years, many things in the networking stack were unchanged since the late 90s/early 2000s, so macos didn't have syn flood protection built in, and while the macos pf had synflood stuff, it only works if the macos host is strictly a firewall, using the syn protection for traffic where macos is an endpoint results in no connectivity.

If they pulled in a more recent pf from either OpenBSD or more current FreeBSD would be welcome. (And you know, a recent tcp stack would be nice too; although they've added in things like MPTCP that they'd need to port forward by 20+ years)