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Thread: PPP over null modem cable between two raspberry pis

  1. #1
    Join Date
    Sep 2022

    PPP over null modem cable between two raspberry pis

    I am trying to establish ppp (point-to-point protocol) between two raspberry pis. Both are configured for a headless setup and have ubuntu server 22.04.1 LTS running. I have connected 3 wires between the two pis. Tx, Rx and GND.
    I followed this link : and assigned a local IP and a remote IP, I am unable to ping from local machine to the remote IP. My understanding is that, after running the pppd command, there should be a ppp0 interface established. This is not happening in my case. Any idea where I might have gone wrong?


  2. #2
    Join Date
    Nov 2008
    Boston MetroWest

    Re: PPP over null modem cable between two raspberry pis

    It's been many years since I've done this, but my first suggestion is to look at the logs. pppd might log to /var/log/syslog or it might use its own log file. Look at your configuration file to see.

    Did you use the "setserial" command as that web page indicates? Are both machines set to the same speed? Does that speed match the one in the pppd command line?

    I assume you're doing this because you don't have free Ethernet ports?
    Last edited by SeijiSensei; September 16th, 2022 at 05:08 PM.
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