Vulnerability Development mailing list archives

Re: "download" caps


From: Andrew Meaden <ameaden () optusnet com au>
Date: Sun, 01 Dec 2002 23:07:35 +1000

Peter Gutmann wrote:

J Edgar Hoover <zorch () totally righteous net> writes:

I'm wondering if you could effectively DoS a capped account for a month by
sending a lot of unrequested data.

This has happened quite a lot here, with full-rate accounts where you get
charged for traffic over a certain level, and rate-limited accounts with no
charges.  The traffic is billed based on what heads your way at the DSLAM, so
you end up being billed for syn floods, traffic aimed at whoever last had your
IP, etc etc etc.  There are no figures on this, but from anecdotal evidence a
large number of users are abandoning full-rate for rate-limited DSL which
doesn't have this problem (I switched after DSLAM records showed I'd done
130MB of traffic in two days while my external router recorded < 30MB).  It's
a pain for everyone, users go from 8MB/s to 128Kb/s, and the provider loses a lot of revenue when people switch to the DOS-proof non-capped (and much cheaper because of the slow speed) accounts. One possible solution is to run at full rate until you've used your monthly quota, then switch to rate-limited, but apparently the DSLAM technology being used makes this impossible.

Peter.



Telcos in .au are starting to introduce plans (optus@home cable, iinet adsl etc) whereby you get a monthly cap that's soft; at the time the cap is reached, the rate is limited (either severely or lightly, depending on the quality of the plan) and no excess data charges are inflicted upon the user.

This technology is definately possible, and the plans look extremely inviting because of this. Especially since a growing number of them are also allowing the running of services (previously almost unheard of on flat rate plans.).

At the end of the day I think everyone prefers a financially safe plan that has permanent connectivity; I know for me at least always-on is much more important than excessive download speeds.

-- Andrew




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