Creation of a mini "cross over" network

Hello, and excuse my bad English :frowning:
I’ve been going around in circles for a while on this problem, so maybe it’s better to put it down completely in order to get some help :wink:
Here it is,
I already have a small local network that includes computers, tablets, smartphones, printer, etc. and it works well.
Recently I integrated a Raspberry PI 3B+ on the advice of my son, who set up the family cloud on it…
After the inevitable trial and error at the beginning, I’ve come up with something quite satisfactory (my goal is to save energy by getting rid of the old power-hungry hardware…)
I still have one unresolved point: I plan to use this Raspberry to create a NAS that will eventually grow as needed without wasting energy…
To do this, I have imagined creating a new link by direct high-performance ethernet cable (cross over) between my “main” computer and the Raspberry. This without modifying the existing WiFi network; so the “big” computer and the Raspberry have both a WiFi interface (192.168.0…) and a second interface (on another network (192.168.1…).
But I’m struggling to set up this new network (between and and nothing works!
Would some people have clearer ideas than mine?

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Using DeepL is totally fine and nothing to excuse :smiley:

What should be the goal of this setup? Why are you trying to create an additional network between computer and RPI? Why not using the existing local network?

Firstly, because a point-to-point network confined between two machines, via Ethernet, is much safer than a more extensive Wifi network (I sometimes have guests who come with their own machines), not to mention young people with their smartphones, all of which is not very secure, without becoming paranoid…
Then, the Wifi speed is lower than what I can get with a direct ethernet connection, on cable today or possibly fibre later, and the speed is the important thing for a NAS

so you like to connect to DietPi from this single computer only? Noone else should have access. And DietPi should be connected to Ethernet only or should it stay connected to WiFi as well? Because of DietPi will stay connected to WiFi as well, you will not gain any security benefit from your direct Ethernet connection because everybody could connect on WiFi still. As well you would connect the RPi to Ethernet to your local network and setup firewall rules to allow the single computer only, which will logout other devises. Anyway, the RPi3 don’t have a real 1Gbits Ethernet interface. Networking Benchmarks | Raspberry Pi Dramble

Yes, you’re right, on further reflection I also concluded that the RPI should be isolated from everything else and dedicated solely to the NAS; this can only bring benefits in terms of performance too, the RPI being dedicated.
In fact I was thinking afterwards, once my trials and tests were completed, to use in RPI 4B or an equivalent machine as there are several out there, the fact of using DietPi allowing to change nothing to the general set-up…

hope you already have one. They are quite expensive atm.

This will remove the possibility to update the system keep things up-to-date.

Better to think of using a firewall to allow access for specific clients only. You could use ufw and fail2ban.

You are right, it may be quite adventurous to hope for a price drop in these years!
And I must admit that I hadn’t thought about the upgrade issue at all, so that’s a bit of nonsense
On the other hand, I lose the advantage of a very fast link between the two machines; I’ve seen add-on cards that would allow that, but I don’t know what it’s worth…

Solution to the power hungry hardware

PROXMOX…create a type 1 hypervisor, the OS itself hosts virtual machines, I currently have gotten rid of a few machines and created virtual machines inside one machine…my OPNSense router (passthru of the an addon dual intel NIC so it’s protected), my diet-pi network advert/junk filter and a few other docker containers (one of which is my personal nextcloud build, and jellyfin “backup” (for if/when my UNRaid server’s PLEX goes on the fritz or I lose network connectivity), my DietPi vm build (for testing), my nginx virtual machine (which could be a docker, but I wanted it a stand alone VM in case something broke), and a OMV mapped to a 500gb harddrive with everyone read/write for basic network storage if needed.

4 machines running on a cheapo I7-3770, w/ 32gb ram. I spent less than $100 on all upgrades and junk for the box and was able to consolidate all those services into one machine

PROXMOX you can passthru hardware to vm’s, so a NAS build can grow as needed

Routing from the “main” computer to the Raspberry pi would have to be done in the internal tables, maybe even “share” a 2nd nic in the computer, not sure how well it would work…it might have to be NAT’ed (possible bridge?)
microHOWTO: Bridge traffic between two or more Ethernet interfaces on Linux