double nat with virtual interfaces

RouterOS General
1

Hi all!
I am quite new to the world of mikrotik.
I am trying to do this setup for a mobile office (on a truck).

I have a mobile office with lan (192.168.0.0/24) with a 4g router and dhcp server on it.
May occur that 4g is not available, and I have to get connectivity from other sources, maybe a private adsl or other.
Since my lan is forced to be 192.168.0.0/24 with some static addresses in it, i probably have address conflict if i directly connect my lan to the external adsl modem that gives me connectivity. It’s quite probable that i found a lan using 192.168.0.0/24.
I thougt that using a mikrotik router i could be able to have a double nat chain to avoid ip conflicts.

LAN internal link eth1 of mikrotik connected to the modem of private ADSL
192.168.0.0/24 ----->nat----->1.1.1.1/30 ----> 1.1.1.2/30 -------> nat -------->ETH1 (of mikrotik with DHCP client enabled) -----------> private ADSL

Can someone help me doing that config?
Is it possible to create the link 1.1.1.0/32 totally with virtual interfaces, so I have not to use 2 phisical ports of mikrotik patched togheter?
Many thanks to all for help!
And sorry for my bad english!!
Riccardo

2

On a single Mikrotik (or any other single device, that’s nothing Mikrotik-specific) it won’t work because all IP addresses, regardles to what interface they are assigned, are considered “local” so an incoming packet for one of them will be processed at L3 layer no matter through which interface it has arrived. But nothing prevents you from using another Mikrotik to implement your second NAT. However, you must be prepared to adapt the “inter-mikrotik” subnet if it eventually collides with the one provided by the ISP.

3

Thank you sindy.
I was on the way to do that.
Now I’m trying to use an old tp-link router as a first nat between the external adsl and mikrotik.
I only use mikrotik to choose between gateways.
I’ll tell you how it works.
Thanks!!
Riccardo