[LEDE-DEV] [PATCH v1 1/1] openssh: disable passwords for openssh server

[Alberto Bursi]

On 02/11/2018 11:54 AM, Yousong Zhou wrote:
> On 9 February 2018 at 08:28, Philip Prindeville
> <philipp at redfish-solutions.com> wrote:
>> From: Philip Prindeville <philipp at redfish-solutions.com>
>>
>> Allowing password logins leaves you vulnerable to dictionary
>> attacks.  We disable password-based authentication, limiting
>> authentication to keys only which are more secure.
>>
>> Note: You'll need to pre-populate your image with some initial
>> keys. To do this:
>>
>> 1. Create the appropriate directory as "mkdir -p files/root/.ssh"
>>     from your top-level directory;
>> 2. Copy your "~/.ssh/id_rsa.pub" (or as appropriate) into
>>     "files/root/.ssh/authorized_keys" and indeed, you can collect
>>     keys from several sources this way by concatenating them;
>> 3. Set the permissions on "authorized_keys" to 644 or 640.
>>
> If forgetting doing this means I may need physical connection like vga
> monitor or serial connection to "unlock" the device, very likely I
> will hate this security enforcement...  It's just the inconvenience
> regardless of whether the said situation should happen.  As a user I'd
> like to keep this level of convenience as using password
> authentication and turn it off when I see it appropriate.
>
>                  yousong
>
>

This is the risk I also pointed out myself in the github PR about this.

Either this patch adds logic to check if there is indeed the right files 
in /files
and aborts building if not found or you risks locking out yourself.

-Alberto