RE: (PM) Filtering Mail Pings
Chad Scott (chad@txdirect.net)
Wed, 21 Jan 1998 08:13:20 -0600
On Wednesday, January 21, 1998 1:09 AM, Stefan Hudson
[SMTP:hudson@mbay.net] wrote:
> On Tue, Jan 20, 1998 at 09:44:18AM -0600, Mia's Virtual Post Office
wrote:
> > The ComOS needs to have something written into it that detects pings
that
> > come in regular intervals and pops people out the moment it detects it.
> > Then we can tell people when they sign up that pinging the connection
is
> > illegal and if they do it they will be popped out.
>
> Unfortunately, this is simply not practical. There are so many possible
> ways of defeating an idle timer that it is not effectively possible to
> detect all of them. For any possible algorithm that could be used detect
> "idle" ports, there is a way to deliberately defeat it. It would be
> far too complicated a system to implement in a terminal server.
>
> I have considered setting up a machine running tcpdump, and writing some
> software to try to detect "keepalive" connections based on that output
> and other things like mail server logs, but it would be hard to write,
> very CPU intensive, and it still would be trivial to defeat it
> deliberately.
It has been mentioned several times before that Lucent should give ComOS
the ability to filter the data that is passed to the idle-timer routine.
In this way, you have a little more control over what the PM uses to
determine activity.
It would still be trivial to defeat, however.
Chad Scott
Network Operations
Internet Direct, Incorporated
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