nanog mailing list archives

Re: de-peering for security sake


From: Owen DeLong <owen () delong com>
Date: Sat, 26 Dec 2015 15:11:13 -0800


On Dec 26, 2015, at 12:50 , Matthew Petach <mpetach () netflight com> wrote:

On Sat, Dec 26, 2015 at 12:34 PM, Owen DeLong <owen () delong com <mailto:owen () delong com>> wrote:
On Dec 26, 2015, at 08:14 , Joe Abley <jabley () hopcount ca> wrote:
On Dec 26, 2015, at 10:09, Stephen Satchell <list () satchell net> wrote
My gauge is volume of obnoxious traffic.  When I get lots of SSH probes from a /32, I block the /32.
[...]
With respect to ssh scans in particular -- disable all forms of
password authentication and insist upon public key authentication
instead. If the password scan log lines still upset you, stop logging
them.

This isn’t a bad idea, per se, but it’s not always possible for the guy running the server
to dictate usage to the people using the accounts.

Also, note that the only difference between a good long passphrase and a private key is,
uh, wait, um, come to think of it, really not much.

The primary difference is that nobody expects to have to remember a private key so we don’t
get fussed when they contain lots of entropy. Users aren’t good at choosing good long secure
passphrases and the automated mechanisms that attempt to enforce strong passwords just
serve to increase user confusion and actually reduce the entropy in passwords overall.


No, the difference is that a passphrase works
in conjunction with the private key, which is
the "something you have" vs the "something
you know" in two-factor authentication.

No… You are missing the point. Guessing a private key is roughly equivalent to guessing a really long
pass phrase. There is no way that the server side can enforce password protection of the private key
on the client side, so if you are assuming that public-key authentication is two-factor, then you are
failing miserably.

With password authentication, there's only a
single solution space for the attacker to
sift through; with private key authentication,
unless you're sloppy about securing your
private key, there's two massive solution spaces
for the attacker to sift through to find the unique
point of intersection.

The point here is that securing the private key is a user task and not under the control of the administrator.
As such, you have to assume sloppy.

Massively different solution space volumes
to deal with.  Equating the two only has meaning
in cosmological contexts.

Or contexts where the user is sloppy about securing their private key, e.g. the real world.

Owen


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