ssh into raspberry without a router

WbrJr@lemmy.ml to Selfhosted@lemmy.world – 28 points –

Hi! I hope this is the right community to ask.

Next week I will be on the road for 5 Days for work. I have quite some spare time, so I thought I would dig up my raspberry project again and hopefully finish it.

I need it with me, because it controls some hardware, so a VPN to home does not work. So only option I could think of, is to connect the pi directly to my laptop via an ethernet cable. As far as I understood from some research is that I would need to install and run an DHCP server on my laptop, which they did not recommend. Alternatively they suggested to just take a router and plug both devices in there. I don't really have a spare router, so that's not an option either.

To be hones it confuses me a little, that there does not seem to be a standard for connecting to a device directly over a single cable and login with a user account.

Any recommendations how I can work on the pi like with ssh?

Thanks a lot!

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As far as I understood from some research is that I would need to install and run an DHCP server on my laptop, which they did not recommend.

Or simply set up the Pi with a static IP.

there does not seem to be a standard for connecting to a device directly over a single cable and login with a user account.

There is. A cable. You just need two non-identical IPs from the same subnet, e.g. 10.0.0.1 and 10.0.0.2 or whichever you want from the private ranges.

I remember from back in the day that you need a "twisted pair” edit: ”cross-over” cable though, or do modern ethernet ports automatically adapt to that now?

Twisted pair refers to the twisting of the wires in the cable to reduce crosstalk.

Crossover cables enable permit connecting two non-sensing ports together.

Right 🤦‍♂️ It has been a while. I corrected it in the original post now.

I hear ya. I know all this stuff, but dammit if it isn't hard to access sometimes! Haha

You're thinking of crossover cables, though I'm not sure if those are still necessary.

Most modern NICs can auto-negotiate the Rx/Tx circuits on either kind of cable, but I'm not sure about RPi.

Only one device needs to be able to negotiate it.

Just about everything made in the last 20 years is capable of doing this.

If I remember correctly, 1000Base-T standard has a requirement that device has to negotiate pinout on the fly. No matter which pin is connected to which. Obvioiusly just randomly wiring a cable up has other problems, like signal-to-noise, but in theory it should work even if you make a cable that's as unstandard as you can make it.

That's amazing. I would love to see the algorithm for that. Hopefully I'll find a nice explainer if I search around.

I think it doesn't matter nowadays. Network interfaces are smart enough to twist them internally, or at least, this is what I experienced. I have no idea when did I had to use specifically a crosswire cable, all of my ethernet cables are patch cables for a while now.

So, it shouldn't be a problem.

I think this method should be the top answer.

I connect directly to devices without a router most working days for work and this is the method we use because it's simple and effective.

This for sure, and bonus points for "USB Ethernet gadget" mode if you have a 4 or zero ;)