backdoor by authorized_keys2 leftovers

Dan Kaminsky dan at
Wed May 11 16:01:14 EST 2011

Sent from my iPhone

On May 10, 2011, at 9:47 PM, Damien Miller <djm at> wrote:

> On Mon, 9 May 2011, Rado S wrote:
>> Hi devs,
>> recently I had to replace authorized_keys on several systems to
>> enforce an access policy change.
>> I was badly surprised that authorized_keys2(!) was still processed,
>> which allowed some old keys to enter the systems again, because I
>> wasn't aware of the file's existance on the server and use by sshd,
>> since this "backward compatibility" isn't documented, not even a
>> historical reference about "obsolete" or "deprecated".
>> Maybe it's time to drop the old stuff not to get haunted by such
>> leftovers again.
> Good point - I just committed a change to remove it for openssh-5.9

I'd document, rather than remove. I think all my systems use authorized_keys2.  You will end up locking users and admins out. 

> -d
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