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Disable NAT on MacIPGW?
Posted by: Durosity on 2025-04-30 03:23:09
I'm using @mactjaap's amazing MacIPRpi on a Raspberry Pi and it's working great, but I'm wondering if it's possible to disable the NAT element and use the IP range I have setup for the VLAN that my vintage network uses? I mainly want to do this simply because.. honestly.. I struggle with some OCD tendencies and having some Macs on a 172.x and some on a 10.x range is kinda messing with my mind, but also I want to be able to use FTP programs between different ranges and that isn't working, and also experiment with other stuff like this.

So I suppose the ultimate question is, can it be done, and if so how? I tried looking at the iptables on the pi but it's been 26 years since I last looked at it and I really don't know what I'm doing with it (and frankly it made me feel stupid because back then I used to know lots about that stuff on linux and this has made me realise how little I can recall!)
Posted by: cheesestraws on 2025-04-30 03:41:23
As far as I know, none of the UNIXy MacIP gateways support totally transparent bridging, aka "pretend to be ethernet", which isn't unreasonable - MacIP isn't Ethernet. So you're stuck with a separate IP network.

You can escape NAT, though, although whether it's worth it depends on how much you like networks (I'm assuming at least a bit because you have multiple VLANs), by creating a new IP network and routing between them. This would solve your FTP issues, for example. To do this, you would need to:
  1. Allocate yourself a MacIP range (I'll assume it's a /24 for the rest of this list) under 10/8. Do not punch a hole in your existing subnet, give it a new range.
  2. Get macipgw to use that range by changing the command used to start it (e.g. if you were using 10.1.0.0/24, macipgw -n <yourdnsserver> 10.1.0.0/24 255.255.255.0)
  3. Make sure that the net.ipv4.ip_forward sysctl is 1
  4. Set up a route for your new subnet on the Pi's upstream router (or use a dynamic routing protocol if you've got a favourite).
  5. Turn off NAT (can't remember how to do this, try to avoid internal NAT)
Posted by: NJRoadfan on 2025-04-30 03:55:28
Either do the above, or implement proxy ARP in macipgw like the hardware MacIP routers do.
Posted by: Durosity on 2025-04-30 06:28:20
  1. Allocate yourself a MacIP range (I'll assume it's a /24 for the rest of this list) under 10/8. Do not punch a hole in your existing subnet, give it a new range.
  2. Get macipgw to use that range by changing the command used to start it (e.g. if you were using 10.1.0.0/24, macipgw -n <yourdnsserver> 10.1.0.0/24 255.255.255.0)
  3. Make sure that the net.ipv4.ip_forward sysctl is 1
  4. Set up a route for your new subnet on the Pi's upstream router (or use a dynamic routing protocol if you've got a favourite).
  5. Turn off NAT (can't remember how to do this, try to avoid internal NAT)
I'll have a crack at that. I feel like it's something within my capabilities.. so expect a message from me later all very confused.. 😀
Either do the above, or implement proxy ARP in macipgw like the hardware MacIP routers do.
That I don't know how to do.. could you give more information on how, and what the benefits of that would be?
Posted by: cheesestraws on 2025-04-30 06:56:53
I'll have a crack at that. I feel like it's something within my capabilities.. so expect a message from me later all very confused.. 😀

Happy to talk to you about it, as always 🙂
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