Share wifi but keep Firewall on

Is this Mac behind a home router? Perhaps the device provided by your ISP?

Or do you just have a Cable Modem (or FiOS modem; or similar)?

If there is a router between your Mac Pro and the outside world, then having your firewall on does nothing, unless you do not trust the other members of your family. The router is already blocking all unsolicited connections from the evil internet.

On the other hand, if you just have a broadband connection (no router), and the Mac Pro is going to be the router, then it is most likely not a smart choice, as A) Internet WiFi sharing uses a very weak WiFi encryption. B) macOS is not really used much as a router, so it is not as well tested as an inexpensive commercial router.

Since you have a commercial router between your home and the Internet, you do not need your macOS firewall. Unless of course, you do not trust your family 🙂

However, you might consider getting a WiFi router. Put it into Bridge Mode (basically turn off DHCP and NAT services in the WiFi router; each WiFi router does this differently, but they all have a way to do it), then plug the WiFi router's WAN port into one of the Billion Bipac 7300's Ethernet ports.

When configured this way (Bridge mode), it will just be a WiFi access point for all your home WiFi devices, it will use less power than your Mac Pro, and it will use much better WiFi security/encryption.

the Mac OS firewall only works as a gateway for specified applications and services, but not Common TCP/IP Protocols and Ports. If your router has its own firewall I would highly suggest you use that instead of the one built into OS X.

In regards to a WiFi router, do you mean something like an Airport Extreme?

That would be a more expensive option, but there are many WiFi routers available in the plus or minus $50 range

<https://www.lifewire.com/best-routers-under-50-4038819>

<Best Cheap Routers for 2018 - CNET>

If you have a home that is difficult to get good coverage, then you can consider one of the Mesh Networking WiFi routers, such as 'eero.com' (only mentioned because I use eero, so I have first-hand experience with this one).

<The Best Wi-Fi Mesh-Networking Kits for Most People: Reviews by Wirecutter | A New York Times Company>

<https://www.lifewire.com/best-mesh-wi-fi-network-systems-4139748>

NOTE: Before I switched to an eero system, I used Apple's Airport routers from 2001 (the original) until 2017 (last year). So I have nothing against them. But I have difficult to cover in WiFi home, so when Mesh Network WiFi devices became available, I switched. I also realize that an Airport Extreme solution is more expensive than many people need, and there are many less expensive solutions that will work just as well.

I will finally say if you are using smartphones or tablets having WiFi always available makes life nicer at home, and the smartphones do not need to cellular data, which may be a limited resource with your carrier plan. And some carriers allow you to use WiFi calling if the smartphone supports it, which can be very helpful if your home is in an area where cellular coverage is weak (again something I experience).

But, if using your Mac Pro is all you really need, and it works for you, just ignore my ramblings 🙂

Those eero routers are pretty expensive, at least IMO, about one and a half or two times the price of an airport extreme, at least in my country.

Absolutely, but my home is a long 2 story house and getting coverage to all parts required multiple Airport Extremes. For me to get coverage over my entire house, I required at least 2 Airport Extremes, and eventually, I had 2 new ones and an old one giving complete coverage. So comparing the price of 3 Airport Extremes (even if I acquired them over time) vs an eero, The eero was actually cheaper. And I could afford the eero as a tech toy (Ooh! Shiny 🙂 ).

But the reason I went down this path is that you can get a very good WiFi router, for not a lot of money, disable DHCP & NAT (Bridge Mode) and have a less power hungry device that is using modern up-to-date WiFi encryption so your neighbors cannot jump on your network and use your bandwidth for free.