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JanSB
just joined
Topic Author
Posts: 1
Joined: Sun Apr 17, 2022 6:10 pm

NAT on two local subnets

Sun Apr 17, 2022 6:22 pm

Hello,

i try to get a simple NAT between two local Networks running but somehow i am completely stuck.

I have two local networks
Subnet A: 172.17.1.X /24
Subnet B: 172.28.10.X/24
they are networks for two separate machine networks without routers and withour public internet access. I want to use a hEX.lite to connect these networks and setup an NAT route that traffic for 172.17.1.80 gets forwarded to 172.28.10.80.

The goal is to be able to reach the HMI on 172.28.10.80 from the Subnet A. I tried to set up a setup an NAT but i am missing something here and i am completly lost at the moment.

Thanks for your help.
 
DeJoe
newbie
Posts: 33
Joined: Thu May 31, 2018 4:26 pm

Re: NAT on two local subnets

Fri Apr 22, 2022 1:14 am

Hi.

Am I right you want to translate traffic with destination 172.17.1.80 to 172.28.10.80?
So the devices on Subnet A can ping 172.17.1.80 and that traffic gets forwarded to 172.28.10.80?

If so you can't achieve that by a simple NAT setup. All devices in Subnet A think of 172.17.1.80 as an IP on their local subnet. They won't use any Gateway to reach that address. And no packets to that address will reach the Mikrotik device on Subnet A.

You can use proxy-arp and NAT in combination to get this working. But it is not a simple setup.

Another solution would be to give the Router on Site A an additional address 172.17.1.80 and then setup dst-NAT to translate incoming packets to 172.28.10.80.

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