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Pi3 to convert Wifi to ethernet

Posted: Sun Jan 14, 2018 7:45 pm
by gwildav
Hi all,
I'm fairly new to Raspberry Pi and networking, but learning.

I have a 3D printer with an ethernet connection, the RepRapPro Ormerod 2.
I'd like to move this to somewhere there is no ethernet. But there is still Wifi.
I was hoping to use the Pi to make some kind of bridge between the wifi and the ethernet port on the 3D printer.
I hope to preserve IP addresses, so I think a 'bridge' is better than NAT.

I've blindly followed this guide: ...
And it seemed to work, except the wrong way around - the guide assumes that the internet and DHCP is via ethernet cable, and that these should be shared via Wifi hub created within the Pi.
I want the opposite- the internet and DHCP are supplied via the existing broadband Wifi hub, but I want to use the Pi to turn the Wifi signal into an ethernet cable signal to and from the 3D printer.
I followed the guide again from the top of the page, but I replaced every reference to 'wlan0' with 'eth0', and vice versa.
I get as far as 'sudo brctl addif br0 eth0' (but as 'sudo brctl addif br0 wlan0' in my swapped version), but the Pi gives an error that the bridge already has an entry.

So, please can anyone help?
-How can I clear the bridge file, so I can write 'sudo brctl addif br0 wlan0' to it? Perhaps that will have errors further on though..
-Or even better, can anyone supply step by step instructions from where I am now, which is a partial way through the guide? The guide above is confusing when it says "Follow the instructions above to set up the hostapd.conf file"- how far above should I go?!

Many thanks,

Re: Pi3 to convert Wifi to ethernet

Posted: Mon Jan 15, 2018 11:23 am
by SurferTim
The bad news is I can't find a way to add a client wifi interface to a bridge. I keep getting "operation not permitted" or something like that.

Re: Pi3 to convert Wifi to ethernet

Posted: Mon Jan 15, 2018 1:54 pm
by piglet
It may be cheaper and simpler in the long run to look for a dedicated solution. I've successfully used something like this where I had ethernet and no wifi on a device:

Re: Pi3 to convert Wifi to ethernet

Posted: Mon Jan 15, 2018 3:38 pm
by gwildav
That's a real pity- I have a Raspi and Touchscreen on the printer already for control, so it seems a shame to have two different pieces of equipment both hooked up.
Thanks both, I'll buy the extra Wifi device.

Re: Pi3 to convert Wifi to ethernet

Posted: Mon Jan 15, 2018 5:35 pm
by mattmiller
May be worth looking into whether the Octoprint setup would work for you

Re: Pi3 to convert Wifi to ethernet

Posted: Thu Jan 18, 2018 7:41 pm
by gambaguru
Since Raspian is basically Debian, instructions for setting up Debian as a router will likely give you what you want.

A Google search on "debian router" (without the quotes) returns these as the first few hits: ... m-scratch/ ... r-gateway/

(Sorry for failing using DuckDuckGo like a loyal Raspberrian...) ... 5-minutes/

Or you could possibly try a dedicated router OS, such as dd-wrt or openWRT, that has been ported to the RPi. Here is a small hint in that direction. (I'd go the other way, myself.) ... berry_pi3/

I almost set up a Pi as just the sort of bridge you want for a friend this week (though for an old laser printer with 10Mbps wired Ethernet rather than for a 3D printer). It should be entirely doable.

I didn't see that project through to completion, though, when I found that I had an old Linksys router (the venerable and admirable WRT54G v.4, same hardware and firmware as the WRT54GL) that I could reflash dd-wrt onto. Configuring the router with dd-wrt firmware as a "Client Bridge" (a matter of picking that mode of operation from a menu and supplying the name of my friend's WiFi network and its password) gave me the bridge at a total cost and environmental impact of zero, whereas we'd have had to buy a new Pi and leave the WRT54G unused in my computer boneyard.

Alas the good ol' WRT54G is of limited use nowadays as a 100Mbps Ethernet and 802.11b/g device in what is now a Gigabit Ethernet and 802.11b/g/n/ac world, so pairing it with an old indestructible HP printer with slow networking is a perfect way of reusing it. (It's also a way to give back a small something tangible -- i.e. hardware -- to my friend, who has given me a lot of hand-me-down computer and photo gear over the years in return for my help with comuputer and networking tech support.)