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RE: Comcast using IPS to protect the Internet from their home user clients?
From: "Aditya, ALD [Aditya Lalit Deshmukh]" <aditya.deshmukh () online gateway technolabs net>
Date: Wed, 10 Mar 2004 10:47:37 +0530

dear frank, 

if you are routing all your scans from a vpn and the vpn connections are encrypted as they always are then is 
impossible that the scan are triggering some kind of signatures. i think while they *might* have a ids installed and 
working, they also might be filtering based on the traffic thresholds ... 

the scan might been ovee the limit and the scannning stops!

out isp used to do this a long ago something like in 2000, but has since stopped 


Anyhow, I noticed that certain vulnerability scans, for example scans
using Nikto and similar tools, when run from a Comcast address show a
different behavior than when they are run from a clear, uncontrolled
Internet connection (i.e. corporate T-3). In fact, it appears like
Comcast has an Inline-IDS (some call it an IPS ;) sitting on its wires,
filtering out certain signatures and blocking subsequent access for a
short period of time. For example, scan progresses, then hangs
inexplicably, then resumes, trips a sig, and hangs again. At the same
time, the same scan from a non-Comcast address continues without any
hick-ups. Targets have been ruled out (up and running, verified at the
same time from different addresses), and connectivity to the rest of the
net remains. It's looks like just the src-dst address pair is used so
that all connections from a Comcast src to that particular dst are
blocked for a short moment (1-5 minutes).

Has anyone else noticed that? Is Comcast actually attempting to keep all
those worms'n'viruses of their clients away from the Internet?

How many other ISP's are known to use IPS's inline to protect themselves
from the 'Net, or protect the 'Net from themselves?

Frank (routing all scans via VPN through corporate hosts ;)

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