Challenge-response mail filters considered harmful (by spammers)

[Alan Connor]

There is SO much misunderstanding (and disinformation) about CR systems here.


Let's say I was going to mail a business. Here's what would happen:


The address that I mailed to would go into the temporary part my passlist
automatically, and any mail from that address for the next 7 days would be
accepted. Likely, all I would get is an auto-response from that address.


The sig would look like this:

--
Please include this signature in any response to this mail. Thank You.

03030328485746362539765473632263748596943754959696 9685747


The first 6 characters are the date, UTC, making it easy to expire the password
in a week, with a different one going out with each mail.

Since including the initial mail in the reply is standard practice in the
business world, and with most individuals for that matter, there is nothing
remotely unusual or discomfiting about the request.

I do the same with any individuals I initiate contact with. No one has ever
said a word about it, except perhaps to ask what it is about.


The procmail recipe, for my fellow hackers out there, is simplicity itself:


:0 B:
* .*030303284857463625397654736322637485969437549596 969685747
inbox

This also goes in the temporary section of my passlist.



To generate the number you can do:

echo "`date -u +%m%d%y`"$RANDOM""$RANDOM""$RANDOM""$RANDOM""$RAND OM""$RANDOM"\
"$RANDOM""$RANDOM""$RANDOM""$RANDOM""$RANDOM"" | sed 's/\(^.\{55\}\)\(.*\)/\1\
/' > file


(if anyone can clean that up for me, I'd appreciate it.)




See? Who is inconvenienced? Can a spammer beat that? NO.


Alan



--
For Linux/Bash users: Eliminate spam with the Mailbox-Sentry-Program.
See: [url]http://tinyurl.com/inpd[/url] for the scripts and docs.



--
To UNSUBSCRIBE, email to [email]debian-user-request@lists.debian.org[/email]
with a subject of "unsubscribe". Trouble? Contact [email]listmaster@lists.debian.org[/email]

[Alan Connor]

--
For Linux/Bash users: Eliminate spam with the Mailbox-Sentry-Program.
See: [url]http://tinyurl.com/inpd[/url] for the scripts and docs.



In my last post on this subject, I made a mistake.


When I send a mail to a business (etc.) the address to which it was sent
is entered into my passlist, but expires after the receipt of one mail
from that address, to allow for auto-responses.

Any further mail from that address would have to have the sig with the
long string in it, or it would be gzipped up in my quarantine directory
for 3 days and an auto-response sent out to it. (this has never happened).



Cheerio,


Alan


--
To UNSUBSCRIBE, email to [email]debian-user-request@lists.debian.org[/email]
with a subject of "unsubscribe". Trouble? Contact [email]listmaster@lists.debian.org[/email]

[Alan Shutko]

Alan Connor <alanconnor@earthlink.net> writes:

> The sig would look like this:
>
> --
> Please include this signature in any response to this mail. Thank You.
>
> 03030328485746362539765473632263748596943754959696 9685747

That would be a bad implementation. First, that's not a valid
signature delimiter. Second, if it were, many MUAs strip off
signatures automatically in quoted replies.

--
Alan Shutko <ats@acm.org> - I am the rocks.
To Split, or not to Split: that is the question.-Amoeba


--
To UNSUBSCRIBE, email to [email]debian-user-request@lists.debian.org[/email]
with a subject of "unsubscribe". Trouble? Contact [email]listmaster@lists.debian.org[/email]

[Ron Johnson]

On Sun, 2003-08-03 at 18:38, Alan Shutko wrote:

> Alan Connor <alanconnor@earthlink.net> writes:
>

> > The sig would look like this:
> >
> > --
> > Please include this signature in any response to this mail. Thank You.
> >
> > 03030328485746362539765473632263748596943754959696 9685747

>
> That would be a bad implementation. First, that's not a valid
> signature delimiter. Second, if it were, many MUAs strip off
> signatures automatically in quoted replies.

For example: Evolution.

--
+-----------------------------------------------------------------+
| Ron Johnson, Jr. Home: [email]ron.l.johnson@cox.net[/email] |
| Jefferson, LA USA |
| |
| "I'm not a vegetarian because I love animals, I'm a vegetarian |
| because I hate vegetables!" |
| unknown |
+-----------------------------------------------------------------+



--
To UNSUBSCRIBE, email to [email]debian-user-request@lists.debian.org[/email]
with a subject of "unsubscribe". Trouble? Contact [email]listmaster@lists.debian.org[/email]

[Steve Lamb]

On Sun, 03 Aug 2003 18:38:03 -0500
Alan Shutko <ats@acm.org> wrote:

> That would be a bad implementation. First, that's not a valid
> signature delimiter. Second, if it were, many MUAs strip off
> signatures automatically in quoted replies.

Not to mention that if the MUA doesn't do it the user should for proper
nettiquette.

--
Steve C. Lamb | I'm your priest, I'm your shrink, I'm your
PGP Key: 8B6E99C5 | main connection to the switchboard of souls.
| -- Lenny Nero - Strange Days
-------------------------------+---------------------------------------------

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.2 (GNU/Linux)

iD8DBQE/LeLtel/srYtumcURAnHkAJ9OZ3VTUwlagBEz/OkRHLTqR3AioACg4BEI
RWnnwzy/aakbntg1tZlHPLM=
=lLNc
-----END PGP SIGNATURE-----