MacOS – How to use mac as a full router with DHCP, DNS, Port Fowarding etc.

dnsinternet-sharingmacosNetworkrouter

I know I can use internet sharing in macOS to share the internet connection provided to one network interface over one or more other network interfaces on my Mac. However, the feature set is VERY limited. No choice of DHCP range. No DHCP reservations. No port forwarding. etc.

MacOS Server has a DHCP server and other services, but none of them actually share the mac's internet connection in any way, nor can they be used to control or add those features to the native macOS's internet sharing feature mentioned above.

Are there any software tools, Apple or third party, that can do what internet sharing does (share my mac's internet connection out over one or more other network interfaces), but with the kind of additional features listed above?

Thanks!

Update: Thanks to the two answers so far that have pointed me to the two pf based solutions. Admittedly, I'd prefer a solution that doesn't require a virtual machine, and a solution that doesn't require command line stuff but further research has pointed me to IceFloor and Murus and a couple of other GUIs for pfctl. However, pfctl seems to be a firewall not a router, and what I want is routing. Still, I'm limited in my understanding of all this and it's possible this is what I want still because…

With some more research and I find this:

https://developcents.com/2013/08/12/routers-switches-firewalls-differences/

Under the Firewalls section it says "Unlike routers and switches, firewalls are network security appliances" and "… most perimeter firewalls also have routing capabilities (although that is not a requirement)."

So… I'm guessing you guys are pointing me to the pfctl firewall utility because it's one of those firewalls that has routing capabilities, meaning if I want to use it purely as a router and not use any of the firewall functionality, I will be able to do that. Is that correct? And does it have included in its routing capabilities the functionality I'm looking for as described in the original question above (specifically, choice of DHCP range, DHCP reservations, and port forwarding)?

I realize it's possible I could answer this myself with enough study of the documentation and of networking in general, but the original reason for the question is because I'm used to setting up Apple Airport base station with the Airport utility and the original question is seeking something with that kind of clarity but for setting up a Mac instead of an Airport base station to do it.

Any of that make sense and can anyone help me, given all that extra info?

Best Answer

Simple...yeah right....

Note: Someone please edit this to include only default commands

Covered in this answer

DHCP (Range, reservations, mask, router, lease time)
DNS
Port Forwarding
Setup
Text Book

DHCP

Range

Option 1: com.apple.nat.plist[1]

sudo cp /Library/Preferences/SystemConfiguration/com.apple.nat.plist /Library/Preferences/SystemConfiguration/com.apple.nat.plist.orig // Backup just incase
sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.nat NAT -dict-add SharingNetworkNumberStart [START IP ADDRESS]
sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.nat NAT -dict-add SharingNetworkNumberStart [END IP ADDRESS]

Option 2: /etc/bootpd.plist

Turn on Internet Sharing
sudo nano /private/etc/bootpd.plist

<key>net_range</key>
        <array>
             <string>[START IP ADDRESS]</string>
             <string>[END IP ADDRESS]</string>
        </array>

Lease Time

Turn on Internet Sharing
sudo nano /private/etc/bootpd.plist// No need for backup it will recreate incase any issues

 <key>lease_max</key>
      <integer>[MAX TIME]</integer>
 <key>lease_min</key>
      <integer>[MIN TIME]</integer>

Subnet Mask

Option 1: com.apple.nat.plist

sudo cp /Library/Preferences/SystemConfiguration/com.apple.nat.plist /Library/Preferences/SystemConfiguration/com.apple.nat.plist.orig // Backup just incase
sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.nat NAT -dict-add SharingNetworkMask [SUBNET MASK]

Option 2: /etc/bootpd.plist

Turn on Internet Sharing
sudo nano /private/etc/bootpd.plist

<key>net_mask</key>
     <string>[SUBNET MASK]</string>

Router IP 1. Turn on Internet Sharing

sudo nano /private/etc/bootpd.plist

<key>dhcp_router</key>
                    <string>[ROUTER IP ADDRESS]</string>

DNS

Change Server

Turn on Internet Sharing
sudo nano /private/etc/bootpd.plist

<key>dhcp_domain_name_server</key>
     <array>
         <string>[DNS SERVER IP]</string>
     </array>

Alter Settings

Option 1: macOS Server

Use macOS Server | DNS Service
Once you turn it on and alter all setting it will say "Set your network DNS settings to [DNS SERVER IP] to use this server"
- Change the Server (how to is above) to this IP address

Option 2: /etc/hosts 4

sudo nano /private/etc/hosts
IP [TAB] DOMAIN

Port Forwarding 5

Setup/Turn on Internet Sharing 6

Open System Preferences
Go to Sharing
Select the pull-down next to "Share your connection from:" and choose an interface
Check off the interfaces you would like to "Share your connection from"
Click WiFI Options and alter settings there
Once finished, Click "OK" then Check "Internet Sharing" on the left

TextBook/Glossary (Not alphabetical)

Router

DHCP: Dynamic Host Configuration Protocol

DNS: Domain Name System

Port

Firewall: macOS Sierra: Firewall pane of Security & Privacy System Preferences

IP Range

Subnet

DHCP Reservations

IP Range: Check if Port is open

Modem: Modulator-demodulator (Who named this???)

Feel Free to edit and add Text Book Terms

Related Solutions

MacOS – How should I set up the firewall and DHCP with an AirPort Extreme and Lion Server

To use the Lion server for DHCP, you need to simply turn off DHCP service on the AirPort Extreme and turn it on in Lion.

To use the Lion box as a firewall it will need to have two network ports - one for LAN and one for WAN. (Unless you want your LAN side to be provided wirelessly (which I don't recommend)).

I'm a big fan of OSX server and use it at home myself...
so here are some other neat things you could do with a Lion server...

Set up your Lion server to provide DNS names and a domain. When using the Lion server to provide IP addresses (DHCP), you can also allow it to provide other info to the clients, like who's providing DNS. So rather than having to use IPs to refer to your machines, you can give them DNS names. This means you don't have to set up static IPs for each device and you don't have to remember IPs!
DNS and domain name examples: macbook.mynetwork.net, airport.mynetwork.net, etc. (mynetwork.net being your domain)

Set up RADIUS authentication with WPA2 Enterprise for your wireless connection. You "pair" the AirPort Extreme with the Lion server. This means that people who want to use your WiFi have to log in with a user and password.
The user authentication is handled by the Lion server - set up your users in the server's directory.

Set up your Lion server to provide software updates to your Macs This means that your server downloads all the updates from Apple and can then serve them to Macs on your network. Saving bandwidth and time (it's alot faster!) You'll need to either manually point the client Macs to the server for their updates or "bind" the Macs to the server in order to change the appropriate settings for this (which is a big topic best discussed elsewhere).

Have fun.

Sharing Internet with Mac and Buffalo WHR-HP-G54

Short answer: you're doing it wrong.

The Buffalo device you've got is a wifi router. Normally this kind of thing sits between your cable modem (or whatever you've got connected to the wall) and the rest of your home network, and redistributes your Internet connection to multiple devices in your home.

If you turn on "internet sharing" on your Mac, you're essentially turning your mac into a wifi router as well. There is no reason to do this. And you're probably creating a "double-NATing" situation as well, which is undesirable. I'm not sure how you've got your network wired up physically, but that could be part of the problem too, I imagine.

So, in short, either get rid of the Buffalo entirely and rely on your Mac's internet sharing to do the same thing, or use the Buffalo to distribute your Internet connection and turn off Internet sharing on your Mac. I would do the latter. So your setup should look like this:

Wall socket -- Cable Modem -- Buffalo -- Computer
                                      -- Another Computer
                                      -- Yet Another Computer

This is the case both on a physical level and on a logical level—the Buffalo sits "upstream" of your computers in terms of networks traffic, whether it connects to them over an Ethernet cable or wifi.