4

I'm curious whether it is possible to use the Pi in the following configuration:

 ╔══════════╗        ╔══════════╗
 ║ internet ║        ║ device 1 ║
 ╚═════╤════╝        ╚═════╤════╝
       │            ╔══════╧══════╗ ░░░░░░░░░░░░░░ ╔══════════╗
       └────────────╢ wifi/router ║ ░░░░ wifi ░░░░ ║ device 2 ║
         cable      ╚═════════════╝ ░░░░░░░░░░░░░░ ╚══════════╝
                        ░░░░░░
                        ░░░░░░                        . . .
                        ░wifi░
                        ░░░░░░  Here is no
                        ░sig-░  cable possible!
                        ░nal ░
                        ░░░░░░
                        ░░░░░░
         cable      ╔═════════════╗
       ┌────────────╢ raspberrypi ║
       │            ╚═════════════╝
       │       Following devices are out of range
     ╔═╧═╗     of the wifi signal:
     ║ S ║     ╔══════════╗
     ║ w ╟─────╢ device 5 ║
     ║ i ║     ╚══════════╝
     ║ t ║     ╔══════════╗
     ║ c ╟─────╢ device 4 ║
     ║ h ║     ╚══════════╝
     ╚═══╝

I need not only internet connection for device 5 and device 4, but also I must be able to log in to device 5 and device 4 using ssh from device 1 or device 2. Is there any possible solution using a raspberry pi? Where the pi is still able to be logged in and just forwarding the network traffic.

If it is not possible to use the pi in this configuration while still be able to ssh in to the pi, is there a possibility to use the pi like a "invisible bridge/switch" then?

I'm trying to accomplish something like this:

router       192.168.  1.  1  (the one and only dhcp, gateway to the internet)
device 1     192.168.  1.  2
device 2     192.168.  1.  3
raspberrypi  192.168.  1.  4 ?
device 4     192.168.  1.  5
device 5     192.168.  1.  6

I found things like this post, but I wonder, why the Pi should act as a DHCP. Is there a way that the wifi/router is the only DHCP there?

  • There is nothing in this question specific to the PI, which would not apply to any computer running Linux. You will get more answers on unix.stackexchange.com/questions – Milliways Nov 4 '17 at 4:10
  • In general you should NOT run multiple DHCP servers on a single network segment. PS If you do ask on U&L specify what distribution you are running and mention this is Debian based. – Milliways Nov 4 '17 at 4:18
  • 1
    Adding a RPi specific note: You can certainly use the RPi as a wireless bridge in this manner, but the performance of the on-board wifi is not stellar. There are lower-cost travel routers (e.g. GLi) that perform better. You might also check out PowerLine solutions if the systems share an electrical system. – bobstro Nov 4 '17 at 7:06
2

After some years there have been found a solution to this specific problem with Raspberry Pi. You very clearly described that you want to have a bridge on the RasPi but this cannot be done with a WiFi client connection to the router. For this it must supported by the WiFi chip but it doesn't. For further information about this look at Raspberry Pi WiFi to Ethernet Bridge for a server?.

Fortunately there is a workaround made available for Raspberry Pi. You can use proxy arp to emulate a bridge. How to do it you can look at Workaround for a wifi bridge on a Raspberry Pi with proxy arp. I would say the ♦ Static configuration of proxy arp there is the right section for your needs.

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