Newsgroups: news.software.b
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: What "cancel" really does (was: squelch control message)
Message-ID: <1988May21.234052.15301@utzoo.uucp>
Keywords: cancel, squelch, Supersedes:
Organization: U of Toronto Zoology
References: <279@comdesign.UUCP> <2124@munnari.oz>, <2115@epimass.EPI.COM>
Date: Sat, 21 May 88 23:40:52 GMT

> ... a very nasty form of attack would be
> possible -- completely shut down a site by posting a series of cancel
> messages.  For example, if the most recent article out of this site
> was <2100@epimass.EPI.COM>, you could post messages cancelling
> articles <n@epimass.EPI.COM> for n from 2100 through some large
> number, making sure that "epimass" appears on the path somewhere.

However, this doesn't work against the increasing number of news systems
that use less-predictable message-ids.  Take a look at the id on this
one, for example -- C News sites are safe against this kind of attack,
and we're not the only ones using date-based message-ids.