Re: Bad server host key: Invalid key length

[Mark Wielaard <mark@klomp.org>]

Hi,

On Sun, Feb 04, 2024 at 09:20:33PM +0100, Frank Ch. Eigler via Overseers wrote:
> 
> > I just upgraded my laptop to Fedora 39 CSB, and now ssh to sourceware is
> > rejected with the above error message thanks to the Fedora crypto-policies
> > openssh.config.  I can work around this easily enough by setting
> > RequiredRSASize to 1024 in my .ssh/config, but surely I'm not the first to
> > run into this?
> 
> You may be the second.  Nuke all the sourceware references in your .ssh/known_hosts and try again.

Yeah, this is a misleading ssh client warning/error:
https://inbox.sourceware.org/20230308105633.GI22818@gnu.wildebeest.org/

= openssh update produces misleading invalid key length warning

Connecting to sourceware through ssh with a newer openssh or crypto
policy might produce a misleading warning about the key length being
too short:

  Bad server host key: Invalid key length

Please don't try to replace your ssh key, there is nothing wrong with
it. The issue is that you might have an old server key in your
~/.ssh/known_hosts file. Simply remove it and reconnect to get the new
server key:

ssh-keygen -R sourceware.org
ssh-keygen -R cygwin.com
ssh-keygen -R gcc.gnu.org

See also https://bugzilla.redhat.com/show_bug.cgi?id=2164016