Is it time to abandon bogon prefix filters?

Robert E. Seastrom rs at seastrom.com
Fri Aug 15 07:22:56 CDT 2008


Randy Bush <randy at psg.com> writes:

>> bogon block     attacks % of attacks
>> 0.0.0.0/7       65      0.01
>> 2.0.0.0/8       3       0.00
>> 5.0.0.0/8       3       0.00
>> 10.0.0.0/8      8794    1.21
>> 23.0.0.0/8      4       0.00
>> 27.0.0.0/8      7       0.00
>> 92.0.0.0/6      101     0.01
>> 100.0.0.0/6     374     0.05
>> 104.0.0.0/5     303     0.04
>> 112.0.0.0/5     775     0.11
>> 120.0.0.0/8     45      0.01
>> 127.0.0.0/8     6       0.00
>> 172.16.0.0/12   3646    0.50
>> 174.0.0.0/7     1       0.00
>> 176.0.0.0/5     1       0.00
>> 192.168.0.0/16  7451    1.02
>> 223.0.0.0/8     10      0.00
>> 224.0.0.0/3     8       0.00
>
> well, we can see why andree wanted to look behind the 1918 stuff.  it is
> the elephant.
>
> thanks, danny!
>
> randy

In other words, our earlier estimate of 60% was way off...  you can
get 92.1% effectiveness at bogon filtering by just dropping 1918
addresses, a filter that you will never have to change.

What's the operational cost trade-off with going after that remaining
7.9%?  I'll betcha it's not justifiable.  Maybe it's time to change
the best current practices we recommend so that they stop biting us in
the ass every time a chunk of our ever-dwindling pool of unused
address space goes into play.

My uncle used to tell this joke:

Q:  Why did the man hit himself in the head with a hammer?
A:  Because it felt so good when he stopped?

-r






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