This is most likely because the host Mac was 1 or 2 OS Versions behind the Target Mac. The Host and Target Mac need to be on the same OS Version. If your Target Mac is on 10.15, then your Host Mac needs to be on 10.15. Hello, everyone. This is a repository discussing about how to install Mac OS Catalina (or newer version) on GPD Win Max. Thanks to all the volunteers who participated in this project. I don't have all their names, but without their effect, this repository won't be possible. These are all the names I know. One big guy for the initial version of EFI. Officially, the operating system that was available on that Mac at the time that you bought it is the oldest version of macOS that can run on that Mac. It's likely that an older OS won't include.

1. Bridge Crosser Mac Os Catalina
2. Bridge Crosser Mac Os X

Am I missing something with this hint? Isn't this what the 'Internet Sharing' feature (System Preferences->Sharing->Internet tab) is for?

Internet sharing only allows one direction access.
This allows communication in 2 directions.
Machine A -- Router -- (Internet and Machine B)
This setup allows machine A to talk to Machine B, and Machine B to talk to Machine A.
Internet sharing would only allow Machine A to talk to Machine B.
Unfortunately, you need to know the IP address of the target machine.. but otherwise this works well.
---
A completely SANE Canadian.

Not true.
This is exactly what Internet Sharing does. Its simply a router so communication is possible in both directions. I have the very same setup here in my house and it works like a charme.

Let's get Rob to change the title of this hint to 'One unnecessarily complicated method of bridging network interfaces.'

You have just set up your mac to be a router, NOT a bridge. A bridge operates at layer 2, not layer 3.
If you had set up a bridge, you would have created a virtual bridge interface and added both network adapters to it. The bridge interface would get a single IP address, and then anything connected to either interface could have an address from the same range, and would use the address of the bridge interface as their default gateway.
This way, broadcasts and multicast packets (such as the Redezvous protocol) would be able to be seen by all machines on both interfaces. In addition, a bridge will participate in Spanning Tree if you have multiple switches in your environment. A common use of bridging on hosts is configuring redundant interfaces to connect to multiple switches, in case a switch or a network link goes down.
Bridging is an actual networking term, and what you have set up has nothing to do with bridging.

Doesn't Rob check these hints before publishing them? Or does Mac OS X need a knowledgeable technical editor to filter out the non-hints? As has already been pointed out, there is already a one-click solution built into the Sharing panel of the System Preferences.

You have over-complicated your network, and as a result you are proposing adding even more complications :-)
You have 2 routers, with 2 separate but probably colliding address spaces.
What you need to do is disable router functionality on one of the boxes (either wired or wireless), and slave the second box to the first - or replace your wireless router with a dumb access point.
Actually, since wireless routers probably have a few wired ports as well, you can get away without a second router altogether. If you run out of wired ports, get a hub or a switch.
This way you have a single address space, all of your devices can see each other, etc. And, you have fewer devices to maintain.
The only caveat is security. If you don't use authentication on your wireless network, you should consider it 'hostile' because you never know who comes to steal your traffic. So lock up your wireless access - and you should be fine.

While I'm happy to have a hints website, some of them seriously need more quality control before they are posted. I am pretty sure this is a long and unnesessary way to network, albeit usually a way your typical PC WEENIE would do most things (my appologies to the original poster, I just couldn't resist taking that little jab at you). I'm childish. Anyhow, if there is anyone out there that is an absolute networking professional please let me know, I have a complex setup and would like to compare notes. In short I have multiple internet lines, one dsl and the other cable. So if anyone is up for it post here let me know. -digitol-

Most people seems to have missed the point of what I was trying to achieve.
To simplify:
Computer A is on my LAN.
Computer B is on my LAN and has internet access.
Computer C is on the Internet.
Computer B has Internet Sharing enabled.
So now, computer A and B can both reach computer C. Yay!
But I also need computer C to be able to reach computer A on my private LAN.
To be able to do that, computer C needs to know where is computer A, so I forced a route (config. on computer C) to computer A that goes through computer B. And I configured computer B to route incoming connections for computer A to the LAN.
Anyone who has a better way to configure computer B to allow access to computer A from the Internet is welcome to reply to this comment.
From what I found though Google searches, there's no way to configure the default Mac OS X Internet Sharing to do port forwarding, or DMZ.
- Guillaume

Bridge Crosser Mac Os Catalina

I read two drastically different descriptions of your setup and goals; but if I just listen to the example in this reply-thread, I don't understand why you don't just port-forward inbound ('from the Internet'; Computer C) traffic to Computer B via your router's undoubted ability to accept port forward commands to a single subnet IP address (like a DMZ, but is still port restrictive).
For example, I have a wired and a wireless LAN both at my workplace.
The wireless LAN is top-level; i.e., it hosts all the standard client/guest computers, printers, etc., and can accept guest access either wired or wirelessly; it also uplinks to the Internet (via cable modem). It is, of course, firewalled, but less-restrictive, to allow more communication in/out and across the LAN. Ffile transfers and freedom of movement/access is critical to workflow, and risk is dealt with by safe practice, virus software, etc. It is vulnerable, and frequently attacked, but no critical or sensitive data lives for long at this level. This is superfluous to our conversation, but is here to explain why *I* need two LAN types, and why I don't just use a wired/wireless combo LAN (as cheap as $15) as others have suggested you just convert to.
The wired-only LAN is at the second level, using its own firewall and router, so that I can protect my sales stations and sensitive data, customer data (credit card info, sensitive files, etc.); it uplinks to the level one LAN.
The computers on the second level need to be able to see/use/access the printers and computers on the first level, and can easily do so by passing IP-specific requests up through the second-level router to the first-level router; as well as access the Internet, which just get passed normally from gateway to gateway. Requests in the other direction are summarily denied, except for the following:
I frequently need to access my primary workstation under the second level from either a computer on the first level, or via the Internet from home. Similarly, our web server also resides behind the firewall and router at level two.
In order to access these computers/services 'from the Internet', I have the first level router set to port-forward, e.g., port 80 requests (HTTP) to the second-level router, and the second level router points those same requests to the web server IP address. The same is true for file access; AFS ports are forwarded to my workstation, as are VNC and SSH port requests. These, of course, are further protected by 128bit passwords and secure sockets.
Any need to access any other computer on the second level is passed through my station as host. This is the 'bridge' to which you refer and seek.
While you have created a situation that works for you, and was free, but, for most people, a $15-$50 all-in-one wireless/wired router combo, which has built-in bridging (i.e., wired and wireless computers receive/can specify IP addresses in the same range and subnet mask) is the best solution, as it also unifies all behind a single firewall. You point out the ultra-cool AirPort as too expensive for your taste, but if you watch the specials, you can get D-Link, Lynksys, or lesser known but just as good brands (like Hawking), that also have printer ports for enabling 'network' printers without resorting to printer sharing via a host, for as little as free, if you watch rebates and such.
e.g., this deal is common, and ones for less that are new with more featurres and with free shipping come along all the time:
[link:]http://dealmac.com/deals/Refurbished-Netgear-WGT624-108-Mbps-802-11-g-4-Port-Firewall-Router-for-15/132194.html[/link:]
HTH

Most wireless routers have a built-in Ethernet switch, so none of this should be necessary. I'm using a Linksys WRT54G with my servers & iMac connected to the ethernet ports and I connect to it wirelessly from my MacBook Pro & Mac Mini.

@gboudrea:
There is a MUCH easier way to do this. Just about any router nowdays will achieve what you need. Furthermore, if you need you can configure multiple ethernet interfaces in your network pane. Multihoming is what I think you may be after.

Well, folks complained about this hint at the time, but four years later, I wanted to do exactly what gboudrea was trying to explain, and his explanation was the only really sufficient one on the internet.
I'm now able to use my Mac Mini to act as a 5ghz radio to serve my TiVo hi-def video via ethernet, without having to buy a separate $80 box. And gboudrea correctly explains how I can connect into the TiVo from within my LAN.
Hours and dollars saved. Thank you.

Estimated reading time: 4 minutes

Docker Desktop for Mac provides several networking features to make iteasier to use.

Features

VPN Passthrough

Docker Desktop for Mac’s networking can work when attached to a VPN. To do this,Docker Desktop for Mac intercepts traffic from the containers and injects it intoMac as if it originated from the Docker application.

Port Mapping

When you run a container with the -p argument, for example:

Docker Desktop for Mac makes whatever is running on port 80 in the container (inthis case, nginx) available on port 80 of localhost. In this example, thehost and container ports are the same. What if you need to specify a differenthost port? If, for example, you already have something running on port 80 ofyour host machine, you can connect the container to a different port:

Now, connections to localhost:8000 are sent to port 80 in the container. Thesyntax for -p is HOST_PORT:CLIENT_PORT.

HTTP/HTTPS Proxy Support

See Proxies.

Known limitations, use cases, and workarounds

Bridge Crosser Mac Os X

Following is a summary of current limitations on the Docker Desktop for Macnetworking stack, along with some ideas for workarounds.

There is no docker0 bridge on macOS

Because of the way networking is implemented in Docker Desktop for Mac, you cannot see adocker0 interface on the host. This interface is actually within the virtualmachine.

I cannot ping my containers

Docker Desktop for Mac can’t route traffic to containers.

Per-container IP addressing is not possible

The docker (Linux) bridge network is not reachable from the macOS host.

Use cases and workarounds

There are two scenarios that the above limitations affect:

I want to connect from a container to a service on the host

The host has a changing IP address (or none if you have no network access). We recommend that you connect to the special DNS namehost.docker.internal which resolves to the internal IP address used by thehost. This is for development purpose and will not work in a production environment outside of Docker Desktop for Mac.

You can also reach the gateway using gateway.docker.internal.

If you have installed Python on your machine, use the following instructions as an example to connect from a container to a service on the host:

1. Run the following command to start a simple HTTP server on port 8000.

   python -m http.server 8000

   If you have installed Python 2.x, run python -m SimpleHTTPServer 8000.

2. Now, run a container, install curl, and try to connect to the host using the following commands:

I want to connect to a container from the Mac

Port forwarding works for localhost; --publish, -p, or -P all work.Ports exposed from Linux are forwarded to the host.

Our current recommendation is to publish a port, or to connect from anothercontainer. This is what you need to do even on Linux if the container is on anoverlay network, not a bridge network, as these are not routed.

The command to run the nginx webserver shown in Getting Startedis an example of this.

To clarify the syntax, the following two commands both expose port 80 on thecontainer to port 8000 on the host:

To expose all ports, use the -P flag. For example, the following commandstarts a container (in detached mode) and the -P exposes all ports on thecontainer to random ports on the host.

See the run command for more details onpublish options used with docker run.