[tlug] Ubuntu 16.04-LTS SSH authentication problems

["Stephen J. Turnbull" <stephen@example.com>]

Charles Muller writes:

 > I've tried upgrading to Ubuntu 16.04 on a few machines, with both
 > Kubuntu and Gnome (in all cases running on VMware), and when I try
 > to SSH to my servers, not only do I get a password prompt, but the
 > password is not accepted. I duly reset the $HOME/.ssh/ permissions,
 > to no avail.

Besides what others have mentioned, the more recent versions of
OpenSSH ssh distributed by MacPorts have (mostly silently) stopped
allowing Protocol 1: ssh-agent simply refuses to accept the passphrase
without telling you why.  This sounds like your symptoms.  Use an old
version of ssh to access hosts that only have access via SSH 1 keys,
and generate a new keypair for use in the future.

ssh itself will tell you if you ask it nicely enough ("gwyn" is an
obsolete host configured for an SSH 1 key):

$ /opt/local/bin/ssh-add .ssh/xemacs.identity
Enter passphrase for .ssh/xemacs.identity: 
Bad passphrase, try again for .ssh/xemacs.identity: 

$ /opt/local/bin/ssh-keygen -l -f .ssh/xemacs.identity.pub
.ssh/xemacs.identity.pub is not a public key file.
$ /usr/bin/ssh-keygen -l -f .ssh/xemacs.identity.pub
1024 SHA256:fGh1RHTA0uIQNr0DQxApFp617fq7bXqaAjRikTdldtM steve@tanko (RSA1)
$ /opt/local/bin/ssh -1 gwyn
key_load_public: invalid format
ssh1 is not supported

That's the kind of thing you'll see if Protocol 1 is the problem.  (On
my host /usr/bin/ssh-keygen is Apple's (old) version, and
/opt/local/bin/ssh-keygen is MacPort's (new) version.)

HTH

Steve