Re: SSH password authentication: User Unknown?

[Scott Klement <midrange-l@xxxxxxxxxxxxxxxx>]

David,

As Aaron said... the issue here is that AIX only supports 8 character 
userids.  Therefore, IBM i userids longer than 8 characters don't work 
by default.

As Bryan said, you can override this by setting an environment variable.

IBM warns you not to use that variable however.  The logic goes 
something like this:  Someone might've "just assumed" that they'd never 
get a userid longer than 8 characters.  As I'm sure you know, in C code 
if you made an assumption like that, there's a high chance of doing 
something like a strcpy() or memcpy() that would overrun a buffer, if it 
was assumed that the input could never be larger than 8 characters.

However, with OpenSSH, I really don't think there's any risk of a 
problem like that.  After all, this is not an AIX-only program.  Most of 
the platforms that OpenSSH is run on do allow more than 8 chars in the 
userid.  So I can't imagine they'd "just assume" that the userid never 
exceeded 8... it wouldn't make much sense in this particular instance.

So, really that's the reason I'm replying :-)   Just to say that I think 
it's okay to use the envvar that Bryan suggested, as long as you're just 
using it with OpenSSH, there should be no problems.

-SK


On 11/6/2014 3:11 PM, David Gibbs wrote:
> Folks:
>
> Has anyone experienced a problem with SSH on 7.1 reporting a user as
> unknown, even though the user absolutely exists?
>
> I can sign on to the system via green screen without a problem.
>
> When I try to connect via SSH, it rejects the attempt.
>
> I ran sshd in debug mode and got the following output:
>
> debug1: userauth-request for user MYUSERID service ssh-connection method
> none
> debug1: attempt 0 failures 0
> Invalid user from 10.199.19.213
> debug1: audit event euid 112 user (unknown user) event 9 (SSH_invldusr)
> input_userauth_request: invalid user MYUSERID
> debug1: audit event euid 112 user (invalid user) event 9 (SSH_invldusr)
> Failed none for UNKNOWN_USER from 10.199.19.213 port 62784 ssh2
>
> The user profile I'm using _is_ a *SECOFR profile ... but the
> sshd_config says that root login is allowed.
>
> Any ideas?
>
> Thanks!
>
> david