Enable remote login via USB Serial on first boot and after updates.

[MarkDarcy]

Hello all,

I notice that the very first time a disk image is booted after having being downloaded from raspberrypi.org, you cannot login via any other means except via the console, even if (as I have done) you have managed to configure a remote login over USB/Serial by mounting the disk in a PC and directly creating/editing the necessary configuration files beforehand.

This situation also occurs after executing:

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rpi-update

or:

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sudo apt-get dist-upgrade

What happens is that a login prompt is displayed at the remote terminal, but then any attempt to login produces the message:

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System is booting up. See pam_nologin(8)

Does anybody know which file I can edit/remove on the disk image before the first boot, or which file I can edit/remove after performing a firmware/distribution update, that will enable me to login over the (already) configured serial connection? It seems authenticaion-module related (i.e. PAM). However, when I looked around for the standard "nologon" files there didn't appear to be any.

When a machine is only accessibly remotely, there is absolutely no way I can simply plug-in a keyboard and a monitor just so I can login that one time immediately after any kind of update. After all, that was the whole point of setting up the remote access in the first place. It appears that I may not be the only person who wants this feature.

Any help greatly appreciated.

Thanks in advance.

[drgeoff]

If Raspbian, use another computer to add any file (even an empty one) with name ssh or ssh.txt to the FAT partition on the card. When the RPi is booted, ssh will be permanently enabled allowing you to ssh in over ethernet. Usual name and password

[MarkDarcy]

Thanks for your response.

In my case, I explained I was accessing via USB/Serial (specifically, having udev spawn a getty when it detects a UART cable on a USB port).

You wouldn't happen to know if there is any workaround for this?

Thanks in advance.

[Paul Hutch]

Check out this thread for info on getting a USB Serial Adapter console login at boot.
viewtopic.php?t=177728

This thread, viewtopic.php?f=29&t=177076&p=1129209#p1129209, and the article it references, http://0pointer.de/blog/projects/serial-console.html, also helped me get this working.

[sdjf]

Paul, how fortuitious! I am running your modified raspbian-lite image (for flashing C.H.I.P) on a pi zero! I cannot for the life of me get ssh working, will serial login work without any extra equipment? I still prefer ssh, but serial is better than nothing. Tried PM'ing you but board will not let me.

[Paul Hutch]

will serial login work without any extra equipment?

If the machine you want to connect the RasPi to has 3.3V TTL asynch serial I/O, then no extra hardware needed. For most PC's you'll need either a 3.3V TTL to USB or 3.3V TTL to TIA-232 adapter board.

BTW It appears PM's aren't enabled right now, probably

[sdjf]

Paul, thank you. It turns out I will not need a serial connection to pi zero, Was able to successfully ssh in using a new ethernet adapter and improved power supplies for both my old Model B's ethernet adapter and the hub on pi zero. Not sure which factor was more important, would take more testing.