nanog mailing list archives

Re: Checking bogon status of new address space


From: "Robert E. Seastrom" <rs () seastrom com>
Date: Tue, 12 May 2009 07:54:49 -0400


James Hess <mysidia () gmail com> writes:

29/256 = 11% of the available address space.  My argument is, if
someone is scanning you from random source addresses blocking 10%
of the scan traffic is reaching a point of very little return for
the effort of updating the address lists, and as we all know it is
getting smaller and smaller.

Granted, if the filters aren't updated very frequently, they're pretty bad.

That's the usual state of affairs, unfortunately.

But.. I would suggest, basically, filtering bogons is still great and
pretty important, it serves as an ongoing deterrant against random
unruly networks trying to pick up the unassigned  addresses, or
treating the space as  "Up for grabs" just because some space  happens
to be unannounced (and unassigned).

Gotta agree with Leo here.  We can't even get people to implement
BCP-38, which is nine years old for crying out loud.  The deployment
level at which bogon filtering is a deterrent to squatting is quite a
bit higher from the point at which it becomes an issue to legitimate
users.

I've considered static bogon filters to be a Worst Current Practice
for years.  If you feel you absolutely must engage in the practice use
a dynamic feed like Cymru's, but honestly, just let it go.

-r










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