On Mon, Aug 11, 1997 at 11:49:00PM -0800, Bruce Perens wrote:
> My final version will not simply deny the connections, but will output
> an SMTP error to them which will cause an immediate mail bounce at their
> end.
I've been using the tcpd "banners" option, with lines in /etc/hosts.deny
that basically look like this:
in.smtpd exim: \
[list of bad hosts/networks]: banners /usr/local/lib/tcpd
Then in /usr/local/lib/tcpd I have a file named "exim" (add links
as needed creating synonyms for in.smtpd and other sendmail-equivalent
services) that contains these two lines:
550-5.7.1 SMTP connection refused from %h
550 5.7.1 Mail [EMAIL PROTECTED] from another host for reason
The tcpd "banners" function means that the connection is not simply
refused, but instead, the text contained in the file corresponding to
the name of the service is transmitted to the client. (The given SMTP
error codes are, I believe, the most up-to-date way of indicating
administrative prohibition for security reasons; see RFCs 2034, 1893,
and 821.)
As for lists of known e-mail spam domains, I know of one site containing
regularly-updated lists at <ftp://ftp.cybernothing.org/pub/abuse/>.
(It is maintained by J.D. Falk, whois is with CAUCE, the Coalition
Against Unsolicited Email.)
I think a Debian spam-blocking package, using TCPD and generalized to
cover all MTAs, would be a good thing, with a couple of caveats. For one
thing, there's a legal issue: if the Debian package contains the actual
net blocks and/or domain names to refuse mail from, that could open the
Debian project to harrassing lawsuits from spammers. You'd probably want
legal advice on this. Probably the package should put the burden of
choosing blocked nets/sites on the individual user, maybe by getting
addresses to block from a file that the package installer would be
required to create (either by hand or maybe with a script that would
pull in lists from given URLs--J.D. Falk's site has a couple of scripts
like that).
DS
--
David Sewell * [EMAIL PROTECTED] | "Where the earth is dry, the
Dep't of Geosciences, Univ. of Arizona | soul is wisest and best."
WWW: http://packrat.aml.arizona.edu/~dsew/ | --Heraclitus
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