BGP Optimizers (Was: Validating possible BGP MITM attack)

Fri Sep 1 02:04:52 UTC 2017

Sorry for now taking up 1/4 of this thread.... 

My words in the last message don't match what I was thinking, but I think you all get the point. I'm sick, maybe I should be in bed instead of on NANOG. 

----- 
Mike Hammett 
Intelligent Computing Solutions 
http://www.ics-il.com 

Midwest-IX 
http://www.midwest-ix.com 

----- Original Message -----

From: "Mike Hammett" <nanog at ics-il.net> 
Cc: nanog at nanog.org 
Sent: Thursday, August 31, 2017 9:02:07 PM 
Subject: Re: BGP Optimizers (Was: Validating possible BGP MITM attack) 

Actually, I do remember that one of them would optimize inbound routes, but only billed on outbound usage (as it was content-focused). My in is over 8x my out, so hrm... maybe I'm on to something. 

----- 
Mike Hammett 
Intelligent Computing Solutions 
http://www.ics-il.com 

Midwest-IX 
http://www.midwest-ix.com 

----- Original Message ----- 

From: "Mike Hammett" <nanog at ics-il.net> 
Cc: nanog at nanog.org 
Sent: Thursday, August 31, 2017 8:55:46 PM 
Subject: Re: BGP Optimizers (Was: Validating possible BGP MITM attack) 

I would like to use a BGP optimizer, but I'm too poor. :-\ 

That said, I'm also an eyeball network, so modifications of my own advertisements are what affects the desired traffic, not so much the outbound routes. I know the BGP optimization industry is weighted towards content networks. 

----- 
Mike Hammett 
Intelligent Computing Solutions 
http://www.ics-il.com 

Midwest-IX 
http://www.midwest-ix.com 

----- Original Message ----- 

From: "Job Snijders" <job at ntt.net> 
To: nanog at nanog.org 
Sent: Thursday, August 31, 2017 3:06:49 PM 
Subject: BGP Optimizers (Was: Validating possible BGP MITM attack) 

Dear all, 

disclaimer: 

[ The following is targetted at the context where a BGP optimizer 
generates BGP announcement that are ordinarily not seen in the 
Default-Free Zone. The OP indicated they announce a /23, and were 
unpleasantly surprised to see two unauthorized announcements for /24 
more-specifics pop up in their alerting system. No permission was 
granted to create and announce these more-specifics. The AS_PATH 
for those /24 announcements was entirely fabricated. Original thread 
https://mailman.nanog.org/pipermail/nanog/2017-August/092124.html ] 

On Thu, Aug 31, 2017 at 11:13:18AM -0700, Andy Litzinger wrote: 
> Presuming it was a route optimizer and the issue was ongoing, what 
> would be the suggested course of action? 

I strongly recommend to turn off those BGP optimizers, glue the ports 
shut, burn the hardware, and salt the grounds on which the BGP optimizer 
sales people walked. 

It is extremely irresponsible behavior to use software that generates 
_fake_ BGP more-specifics for the purpose of traffic engineering. You 
simply cannot expect that those more-specifics will never escape into 
the global DFZ! Relying on NO_EXPORT is not sufficient: we regularly see 
software bugs related to NO_EXPORT, and community-squashing 
configuration mistakes happen all the time. 

Consider the following: if you leak your own internal more-specifics, at 
least you are the legitimate destination. (You may suffer from 
suboptimal routing, but it isn't guaranteed downtime.) However if you 
generate fake more-specifics for prefixes belonging to OTHER 
organisations, you essentially are complicit in BGP hijacking. If those 
fake more-specifics accidentally leak into the DFZ, you are bringing 
down the actual owner of such prefixes, and depriving people from access 
to the Internet. Example case: 
https://mailman.nanog.org/pipermail/nanog/2013-January/054846.html 

> reach out to those 2 AS owners and see if they could stop it? 

Yes, absolutely! And if everyone of the affected parties of this 
localized hijack leak (or should we say 'victims') reaches out to the 
wrongdoers, they contribute peer pressure to rectify the situation. Just 
make sure you assign blame to the correct party. :) 

> Or is it something I just have to live with as a traffic engineering 
> solution they are using and mark the alerts as false positives? 

No, this is not something we should just accept. The Default-Free Zone 
is a shared resource. Anyone using "BGP optimizers" is not only risking 
their own online presence, but also everyone else's. Using a BGP 
optimizer is essentially trading a degree of risk to society for the 
purpose of saving a few bucks or milliseconds. It is basically saying: 
"The optimizer helps me, but may hurt others, and I am fine with that". 

An analogy: We don't want transporters of radioactive material to cut 
corners by using non-existant roads to bring the spent nuclear fuels 
from A to B faster, nor do we want them to rely on non-robust shielding 
that works "most of the time". 

We share the BGP DFZ environment, 'BGP optimizers' are downright 
pollution contributors. 

Kind regards, 

Job 

ps. If you want to do BGP optimization: don't have the BGP optimizer 
generate fake BGP announcements, but focus only on manipulating 
non-transitive attributes (like LOCAL_PREF) on real announcements you 
actually received from others. Or Perhaps BGP optimizers shouldn't even 
talk BGP but rather push freshly generated TE-optimized routing-policy 
to your edge boxes. Or perhaps the 'BGP optimizer' vendors should come 
to IETF to figure out a safe way (maybe a new AFI/SAFI to manipulate 
real announcements)... there are ways to do this, without risk to others! 

p.s. providing a publicly available BGP looking glasses will contribute 
to proving your innocence in cases like these. Since in many cases the 
AS_PATH is a complete fabrication, we need to manually check every AS in 
the AS_PATH to see whether the AS carries the fake more-specific. A 
public looking glass speeds up this fault-finding process. If you don't 
want to host a webinterface yourself, please consider sending a BGP feed 
to the Route Views Project or RIPE RIS, or for something queryable in a 
real-time fashion the NLNOG RING Looking Glass http://lg.ring.nlnog.net/ 