seligman at nevis.columbia.edu seligman at nevis.columbia.edu
Thu Oct 20 07:02:03 EDT 2005

In the past year or so, the number of invalid login attempts on all
our machines has soared, especially on machines located in the Nevis
Annex.  To block these attempts, I've installed DenyHosts
<http://denyhosts.sourceforge.net/> on all the machines in the Nevis
Linux cluster.

To put it simply, if there are too many failed login attempts from a
given IP address to a machine on the cluster, then the offending IP
address will be blocked from all connections to that machine for a
given time.

I'm deliberately being vague about how many failed attempts, in what
time intervals, and how long the block takes place.

This should have no effect on legitimate users of our systems, unless
you regularly have a problem typing in your user name and password.
If you feel that you've been accidentally blocked by this policy, let
Bill Seligman know and I'll take care of it.

Note that this protection does NOT apply to Linux boxes that are not
part of the cluster, nor to laptops in the Annex.  Be warned:
outsiders will continually try to login to your box.  Make sure your
services are configured appropriately.

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