From: "William Herrin" <bill@herrin.us>
> So, here, you mean customers of such as "Road Runner Business", who
> have an office full of workstations and maybe some servers.
Correct.
> The goal, unless I badly misunderstood it, was to *drop forged traffic
> coming from this sort of source (assuming you generalize "my PC at
> home on a cablemodem" as the limiting example of this class, which I
> do).
Indeed. But it isn't achievable. $Random_SOHO will continue to be
hacked on a regular basis. He doesn't have someone working for him
with the skill to prevent it. Further victimizing him with a game of
whack-a-mole helps nobody.
Besides, his failings aren't important to us. What's important to us
is that his failings don't impact us. We achieve that by insisting
that his ISP not leak his forged packets on to the public Internet. It
would be nice if his ISP didn't accept the forged packets at all, but
that's really not our problem and we don't need to make it our
business.
It's possible I badly misunderstand how things like unicast-rpf work,
Bill. I run much tinier networks than most people here.
But what I *do* understand of it is: you have to run it *at the edge
concentrator*, cause that's the only device which knows which packets to
accept... since *it assigned the address for the link*.
When I say "drop forged traffic coming from...", *who I mean is 'his ISP'*,
as you suggest in the next graf. I don't see that there's anyway to *know*
packets have a forged address anywhere north of the edge of the lowest tier
IAP the connection is served from.
Did I miss something? Or was I simply unclear?
>> 2. A BGP origin-only network is required to secure its BGP-speaking
>> borders against source address spoofing. It may also secure
>> spoofing
>> from downstream networks (and in fact it SHOULD do so) but it
>> avoids
>> the IDP so long as its BGP-speaking borders are secured.
>
> This is the next size up of edge network; a buyer of transit.
>
> This item does no good; you're expecting *the potential bad actor*
> *not to act badly*.
At last count there are fewer than 45,000 such systems worldwide, not
millions upon millions like in group 1. This is a manageable number of
potential bad actors to whom the IDP would apply.
Yes. These are the people to whom edge nodes and private non-BGP nets
speak; the tier 3 4 and 5 network providers who run edge concentrators
and assign addresses.
Also, we're not looking to catch bad actors here. We're looking to
catch sloppy actors. We catch bad actors at step 3 by spanking their
upstream transit ISPs for failing to prevent source spoofing.
...which you would detect ... how? *Those* aggregator networks have
no contractual reason to know what's a valid address coming to them,
unlike the networks to which end sites attach directly.
> *This* is Road Runner. Also Comcast, Mindspring, and the other Top 40
> eyeball networks. It is also, of course, larger carriers who sell access
> in addition to more traditional transit and possibly peering.
Correct.
> AFAICT, this is the spot where source-address-spoofing needs to be
> *enforced*;
Unfortunately, it's also the spot where system complexity reaches a
point where as a purely technical matter, source address filtering
isn't always possible. You can filter your customers based on the
routes they say they plan send you and you can filter your own
internal networks based on the addresses you assign but filtering your
peers for falsely sourced packets can be as intractable as filtering
your upstream for falsely sourced packets.
I don't believe that's what I said.
Filtering based on routes doesn't help; that's *destination address*, not
source, no?
Yes, filtering your peers, or even transit customers, is effectively
impossible; it has to be done where addresses are handed out.
>> 4. Applying the IDP _does not_ mean you cut off the network.
>> That'll
>> piss of your customers as much or more than it pisses off theirs.
>> The
>> position is untenable. Instead, the IDP consists of redirecting the
>> offender's public presence web sites to a web site which proclaims
>> the
>> IDP, lists the causes of the IDP and lists the actions required to
>> lift the IDP.
>
> Unless I misunderstand you there, you're suggesting that inbound
> HTTP to
> public websites *operated by the spoofing entity* should be
> redirected
> to a site that shames them? Yeah, that will piss them off less...
> 
I don't care about about pissing them off. I care about pissing off my
customers. My customers will be pissed off if they can't reach their
customers and suppliers. Who will often be hosted by the target of the
IDP. But will much more rarely be the target of the IDP.
Ok; I apologies; I have laid the bike down in the sandy corner at
this point. Huh?
>> To ask the CEOs to authorize cutting off access to a competitor's web
>> site with the full support and approval of a group of recognized
>> Internet luminaries?
>
> The problem with that sub-approach is that luminaries (of the scale that
> everyone will automatically listen to them), as Jon Postel has said, do
> not scale.
Which is A-OK because if we're applying more than 1 or 2 IDPs in a
year to folks who weren't intentionally bad actors then we're doing it
wrong. It shouldn't ever "scale."
Yes, but you can't measure such a panel on output, you have to measure
it on *input*, no?
Cheers,
-- jra
