Re: SSH probes?

[Valdis.Kletnieks () vt edu]

On Wed, 12 May 2004 09:03:57 BST, iglope said:

> one time we have  : authentication failure;
>
> > May  9 21:35:10 evita sshd(pam_unix)[16374]: check pass; user unknown
> >  
> Another we have :  check pass; user unknown
>  isn't a way to discover a valid user for next brute force session ?
> may be u have to tune your ssh to send the same msg for valid and 
> invalid user ?

*You*, as the system admin, are told whether it's a valid userid
with a bad password, or an invalid userid - because your reaction to
the incident may differ based on which it is.

That doesn't mean that the attacker/user *at the far end* is able
to detect the distinction.

Having said that, there *was* an issue with SSH and PAM support a while ago,
where a timing attack would tell you which it was.  It shouldn't be an issue if
you're at a current release....

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