SSH key compatibility in latest Rasbian


#1

Spent a good hour last night trying to get passwordless SSH working with
my new zero W.

Managed to set the /boot/ssh file and get wifi running by editing the SD
image for a headless setup, but SSHd flat out refuses to accept my
key pair for authentication. Password authentication works fine.

I’m using a DSA key which works with every linux server I’ve ever tried,
but the setup on the latest raspbian will not accept it. It doesn’t see it
as a valid protocol? (NB I am 100% sure this is not the usual permissions thing)?

Am I missing something obvious, or do I have to use RSA keys?


#2

Did some digging.

Rasputniks Golden rule: “if in doubt ask in public and embarrass your brain into
figuring it out”

OpenSSH 7 has deprecated DSA keys, see:

https://www.gentoo.org/support/news-items/2015-08-13-openssh-weak-keys.html

I was a little confused as the version on this Raspbian is reporting as

“OpenSSH_6.7p1 Raspbian-5+deb8u3, OpenSSL 1.0.1t 3 May 2016”

but the client on OS Sierra is 7.x. It’s my ssh client that’s refusing to use
my unfashionable key, not the server.

:facepalm: