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Can't Get Linux Host to Communicate With Mac VM on a Isolated Network


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I am trying to get my MacOS (High Serria) virtual machine to communicate with my host (Fedora 27) on an isolated network bridge. The VM runs on a QEMU, and I created an isolated network bridge on Linux using Virt Manager.

 
Normally, there are two networks that are connected to the VM, the public network (where the VM can see other local devices and access the network on the internet) and an isolated network (where my guests and host can communicate between each other but can't see anything else).
 
If I try to access my Mac VM through the public network, it works just fine. However, when I try with the isolated network, it never works. I even tried to make the public network inactive to see if I can force MacOS to use the isolated network, but that didn't help.
 
I was able to get a Linux/Windows guest VM to communicate between the isolated bridge, but for some reason, I just can't figure out why it is not working on MacOS.
 
Attached below is a picture of how I configured the Isolated Network on MacOS:
post-1274387-0-19142500-1514784726_thumb.png
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What's the subnet used on the public network? Post the IP settings configured on each interface of your devices.

 

The subnet mask for the public network is 255.255.255.0

 

For the IP settings, do you want me to show you the setting I used on my Windows/Linux VM, or do you want me to show set up the Public Network on my Mac VM?

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I ask the subnet and you give me the mask and no info for the IP settings of your systems...  -_-

 

So I'll ask again, what IP subnet (and mask) are you using on the public network and what IP address did you assign on each system for each network ?

 

But you may not understand those questions (or my English), so just fill-in as listed below:

Public network: x.x.x.x /nn

Isolated (private) network: 192.168.100(.0) /24

I will admit that this is the first time I actually dug into networking. So I don't actually know the terminology that well currently. 

 

Note: I had to move my computer to the dorms. So I had to make some changes to my qemu script. Interesting enough, macOS states that Isolated Network is not connected. I hope this information is helpful, unlike my last reply. 

Linux host:

1) Public interface: 134.154.40.53/21

2) Private interface: 192.168.100.1/24

3) Default gateway: 0.0.0.0             # This is what `route -n` told. I never actually created a gateway IP for the bridge

 

Mac VM:

1) Public interface: 10.0.2.15 / ?? # Wasn't sure how to get the other part on macOS...

2) Private interface: 192.168.100.52 /24 # That is what it is supposed to be, but `ifconfig` doesn't acknowledge it.

3) Default gateway: ??? # Doesn't list it on the Isolated network, but the public network's gateway is 10.0.2.2

 

Is the reason why my Mac VM and Linux Host can't communicate with each other have to do with the fact that the gateway IP address has not been set?

 

I can also provide ifconfig for both Linux and Mac if you like.

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Well, I don't even understand how these 2 x systems could possibly communicate on the Public network...

  •  
  • Linux host is on subnet 134.154.40 /21 (i.e. subnet 255.255.248.0 with host range 134.154.40.1 to 134.154.47.254, Bdcst = 134.154.47.255)
  • Linux host has no Default Gateway
  • Mac VM is on subnet 10.0.2. / ???
  • Mac VM has Default Gateway 10.0.2.2

Unless the Linux host benefits from a proxy gateway on the Public network, there's no way these 2 could communicate over it.

 

This is one of the changes I had to do to my hackintosh config. Since my school only support Wifi I had to fall back to using `-netdev user`. So as a result, my host and guest can't see each other.

 

When my desktop was at home, it was actually connected to a bridge.

 

For your info the "/xx" of a subnet/ip address corresponds to the size of the subnet mask, i.e. the number of bits for the network part of the 32bit IP address. For instance, in post #1, you attached a screenshot of the IP settings of the Mac VM Private network: 192.168.100.52 with subnet mask 255.255.255.0. That equates to 192.168.100.52 /24 because the subnet mask is 24bit long (255 in decimal is 11111111 in binary, so 3 x times 255 means 3 x times 11111111, i.e. 3 x 8bits = 24bits).

 

Oh, so a mask like this, 255.255.255.255 would be 32, 255.255.128.0 would be 17, but something like 225.0.225.0 would be invalid.

 

 

On the other hand, no reason why they could not communicate on the Private network.

 

Anyway, this is not a Hackintosh issue, it seems a simple matter of getting network cables correctly plugged into the right interface/LAN, LAN ports enabled (in case switch ports are down) and getting your IP settings right. Get some local help on networking matters and local physical settings. Avoid breaking a local network by plugging things in with incorrect settings, especially as you manually statically define them.

Virtualization has got me rather curious about networking. It definitely would be best for me to study the foundations of networking. I am going to look up some tutorial on networking and doing Linux bridges on my next break.

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