Passwordless SSH login

[Robert Heller]

At Wed, 10 Feb 2021 19:10:49 -0800 "Ubuntu user technical support, not for general discussions" <ubuntu-users at lists.ubuntu.com> wrote:

> 
> Content-Type: text/plain
> 
> ** Reply to message from Robert Heller <heller at deepsoft.com> on Wed, 10 Feb
> 2021 19:26:23 -0500 (EST)
> 
> > At Wed, 10 Feb 2021 15:49:35 -0800 "Ubuntu user technical support, not for
> > general discussions" <ubuntu-users at lists.ubuntu.com> wrote:
> > 
> > > 
> > > Content-Type: text/plain
> > > 
> > > I have set up SSH between two computers on my LAN and am trying to disable
> > > password login.  SSH works between the computers.  I can login using
> > > public/private keys.  What I have not been able to do is disable the password
> > > login.
> > > 
> > 
> > Check the IdentityFile setting in /etc/ssh/ssh_config
> > 
> > You need to make sure it is set to:
> > 
> >    IdentityFile ~/.ssh/id_rsa
> >    
> > I think Ubuntu sets it to:
> > 
> >    IdentityFile ~/.ssh/id_ecdsa
> > 
> > by default.
> 
> Looking at /etc/ssh/ssh_config there is no IdentifyFile parameter, all are
> commented out.  Which system does this need to be set, all of them or the
> client or server?
> 
> When I generated the keys I specified rsa.  I would think that would be enough
> for everything to work.

It needs to be set on the originating machine.  Do a "slogin -v" to see what 
it is doing.  This should be enlightening.  It is possible that the compiled 
in default is something other than ~/.ssh/id_rsa and the -v option will tell 
you that.  If it is in fact something else, you need to include an 
IdentityFile setting like I showed above.  You might need to do it on the 
"other" machine if you ssh both ways.

> 
> 
> > > The instructions I am using
> > > <https://www.linuxbabe.com/linux-server/setup-passwordless-ssh-login> says to
> > > edit /etc/ssh/sshd_config and change "PasswordAuthentication" from "yes" to
> > > "no" and change "ChallengeResponseAuthentication" to "no".  That did not work
> > > as I can still SSH to the computer and login to the computer using the
> > > password.
> > > 
> > > When I edit /etc/ssh/sshd_config "PasswordAuthentication" is commented out so I
> > > removed the comment and changed "yes" to "no". 
> > > "ChallengeResponseAuthentication" was not on the config file so I added it. 
> > > What else do I need to do?
> > > 
> > 
> > -- 
> > Robert Heller             -- Cell: 413-658-7953 GV: 978-633-5364
> > Deepwoods Software        -- Custom Software Services
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> >                                                                                      
> > 
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-- 
Robert Heller             -- Cell: 413-658-7953 GV: 978-633-5364
Deepwoods Software        -- Custom Software Services
http://www.deepsoft.com/  -- Linux Administration Services
heller at deepsoft.com       -- Webhosting Services