Logging Login Attempts

Iain Morgan imorgan at nas.nasa.gov
Fri Oct 8 09:37:45 EST 2010

On Thu, Oct 07, 2010 at 14:39:13 -0500, Perry Wagle wrote:
>    LogLevel VERBOSE logs the ipaddress of the attempt on a "signon that
>    exists", but not which signon name.
>    -- Perry
>    On Oct 7, 2010, at 9:51 AM, Iain Morgan wrote:
>    On Wed, Oct 06, 2010 at 18:07:29 -0500, Perry Wagle wrote:
>      I have passwords turned off, and require keys to match.  The zombie
>      armies swarming outside are trying brute force attacks that in part
>      involve guessing login NAMES.  If they guess the wrong NAME, this is
>      logged in syslog.  If they guess a working user name, then the
>      attack has PARTIALLY SUCCEEDED, but this information is IGNORED.
>      That is, it is not logged.  If the zombie army has tell when it has
>      found a working user name, then it might concentrate on finding its
>      key, and I will be none the wiser.  I will not see that happening.
>      I can get this info by turning logging to DEBUG, but then it is very
>      noisy.  I do not understand why failed attempts to login to my
>      account are not logged.
>      Why is this, and how do I get it fixed?
>    Try verbose rather than debug.

Actually, the attempted username, source IP address, and source port are
logged. This is done in auth.c. At least that is the case in cvs HEAD
and looks like it goes back at least as far as 5.1p1.

    274         authlog("%s %s for %s%.100s from %.200s port %d%s",
    275             authmsg,
    276             method,
    277             authctxt->valid ? "" : "invalid user ",
    278             authctxt->user,
    279             get_remote_ipaddr(),
    280             get_remote_port(),
    281             info);

Note that in the case of password authentication, authlog is a pointer
to logit(), whereas for all other authentication methods it is a pointer
to verbose().


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