A seed for the concept of a network router

A seed for the concept of a network router

[Marek Paśnikowski]

Dear All

I am struggling to identify the most basic information to take the first
step towards building a Guix-based network router.  I would like to ask
for a minimal service configuration to meet the following goal:

I have a fanless mini-computer with two ETH interfaces.  It currently
sits under a proper router device like all the other devices in my LAN.
I wish to be able to physically hook it up between the router and the
WAN modem in such a way, that all incoming traffic (except one SSH port)
gets immediately forwarded to the router, as if there was nothing else
between the modem and the router.  Bonus points if it is possible to
fake the MAC address.

The underlying idea is that I would then be able to experiment with all
the available options and concepts without fear of bricking my learning
process.  Thanks to the machine being an actual computer, I have the
ability to connect a display and a keyboard to really break the concept
of routing down to its atoms and come back safely to a previously
working configuration.

So, what is the first step in this journey?

Re: A seed for the concept of a network router

[Felix Lechner via]

Hi Marek,

On Sat, Jul 13 2024, Marek Paśnikowski wrote:

> So, what is the first step in this journey?

Which device do you have?

Kind regards
Felix

Re: A seed for the concept of a network router

[Marek Paśnikowski]

Felix Lechner via <help-guix@gnu.org> writes:

> On Sat, Jul 13 2024, Marek Paśnikowski wrote:
>
>> So, what is the first step in this journey?
>
> Which device do you have?

I am back from my vacation.

It is a Starlabs Byte,
https://starlabs.systems/pages/byte
but I do not think it really matters, as I have already achieved desktop
functionality on that computer.

I have found an interesting blog post that may be just enough for me to
get started:
https://blog.tjll.net/building-my-perfect-router/
Upon initial reading, it seems relatable to my hardware and to the Guix
way of configuration.

Re: A seed for the concept of a network router

[Maxim Cournoyer]

Hi Marek,

Marek Paśnikowski <marek@marekpasnikowski.pl> writes:

> Dear All
>
> I am struggling to identify the most basic information to take the first
> step towards building a Guix-based network router.  I would like to ask
> for a minimal service configuration to meet the following goal:

I think you'd be best served by the "bare-bones.tmpl" template which can
be found in the Guix sources under gnu/system/examples/bare-bones.tmpl.

Be aware that it is not exactly light in terms of disk space: the last
time I generated a disk image from this configuration, it weighed more
than a GiB!

> I have a fanless mini-computer with two ETH interfaces.  It currently
> sits under a proper router device like all the other devices in my LAN.
> I wish to be able to physically hook it up between the router and the
> WAN modem in such a way, that all incoming traffic (except one SSH port)
> gets immediately forwarded to the router, as if there was nothing else
> between the modem and the router.  Bonus points if it is possible to
> fake the MAC address.
>
> The underlying idea is that I would then be able to experiment with all
> the available options and concepts without fear of bricking my learning
> process.  Thanks to the machine being an actual computer, I have the
> ability to connect a display and a keyboard to really break the concept
> of routing down to its atoms and come back safely to a previously
> working configuration.

Your other questions appear to be more related to networking than to
Guix itself; there are many resources out there detailing how to do this
kind of thing in various ways -- your would probably use some command
line interface such as 'ip' to setup route and networks.

Once the required command line is known, a one shot Shepherd service can
run it at boot to persist the network configuration.

-- 
Thanks,
Maxim