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UUnet blocking ICMP ECHO for select sources/destinations ?
From: Kai Schlichting <kai () pac-rim net>
Date: Wed, 14 Jun 2000 15:08:00 -0400


Greetings.

  How many people here are running their own ping/traceroute/wget tools and
feed the resulting responses into some form of database (MRTG, if you will)
to get an idea how ping times to certain points in the network are
changing over time?

It appears that UUnet is selectively blocking such probes (upon major
customer request?), in this case: pings from a single host (and only
that single host) in my network to 157.130.178.1 , a Seattle border
router to Amazon.com . As it appears, the goal is not to prevent denial
of service attacks (5 ping packets every 5 minutes is less than the
traffic load of an average daily customer of Amazon), but to hinder
legitimate QoS analysis of connectivity to Amazon (and as such through
UUnet's network itself).

I, and certainly others, deem it very necessary to know that major
web sites are or have been unreachable or hardly reachable during
certain times for customer service and quality-of-service control
purposes (yes, this is driving buying decisions for connectivity).
Outages/bad performance in multiple directions are a sure indication
of larger problems.

Are some UUnet border routers so busy that they can't afford even a
miniscule amount of ICMP traffic? Blocking it for single source/
destination pairs just doesn't make sense, other than that there
is something (QoS-related) to hide.

What pisses me off the most is that while Amazon (along with Ebay and
a couple of other high-profile sites) may have corporate brain damage
bad enough to filter all ICMP, not just rate-limit it or limit it
to certain parts of their infrastructure, but a major backbone provider
doing the same?

Input please. Comments like "well, use another machine, or use http
GET instead of ping to measure performance" are not helpful: I am
fully capable of doing an end-run around these blocks any day.

Thanks,
bye,Kai




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