[systemd-devel] Starting the sshd service on a 'non-bash' system

[Mark Corbin]

>
> On Thu, Aug 1, 2024 at 8:41 AM Mark Corbin <mcorbin at lunarenergy.com>
> wrote:
>
>> Hello
>>
>> I was wondering whether anybody has any experience of running the sshd
>> service successfully on a system with a 'non-bash' shell?
>>
>
> mark, this is a systemd list, people here may know about openssh but  it
> is not the right place to ask
>

Hello Cristian

My reason for posting to the systemd list is because this currently looks
like a systemd issue and not an openssh issue. Sorry if I didn't make that
clear:

Some extra debug messages that I've added to both systemd and sshd show
> that the incoming socket gets closed somewhere between the handover from
> the systemd socket service to the systemd sshd service. This results in
> sshd being unable to get any peer details. The call to getpeername in
> service_spawn fails with ENOTCONN.
>

My investigation so far shows that the systemd socket service listens for
incoming ssh connections, accepts incoming connections and prepares to
spawn the sshd service, but somewhere during this process the socket gets
closed before sshd is spawned. Tracing through the systemd code shows that
the socket has been closed by the time getpeername is called in
service_spawn (the call fails with ENOTCONN). This is immediately before
systemd attempts to spawn the sshd process in src/core/service.c.

Regards

Mark


On Sat, 3 Aug 2024 at 18:25, Cristian Rodríguez <crrodriguez at opensuse.org>
wrote:

>
>
> On Thu, Aug 1, 2024 at 8:41 AM Mark Corbin <mcorbin at lunarenergy.com>
> wrote:
>
>> Hello
>>
>> I was wondering whether anybody has any experience of running the sshd
>> service successfully on a system with a 'non-bash' shell?
>>
>
> mark, this is a systemd list, people here may know about openssh but  it
> is not the right place to ask.
>
>
>
>> I can't see anything obvious in either the systemd source that suggests a
>> dependency on bash.
>>
>>
>>
> IF systemd wants bash, it would explicitly call /bin/bash or have scripts
> with the proper shebang. otherwise a posix compatible shell should work.
> Shells that are widely tested as default are bash and dash, stick to one
> of those.
>
>
>

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*Mark Corbin *
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