[ On Tuesday, April 29, 2003, Kevin P. Fleming and others wrote: ]
> Subject: Re: [Exim] Idea to slow down spammers
>
> This is already being done, check the list archives for "teergrube".
[ On Tuesday, April 29, 2003, Richard Welty and others wrote: ]
> Subject: Re: [Exim] Idea to slow down spammers
>
> it's called a tarpit.
Technically it's more properly called something along the lines of
"response rate limiting". The idea is that the mailer simply does not
respond as fast as it possibly can to anyone it doesn't like.
Personaly I've found that any and all errors triggered by a client
should trigger response rate limiting, and for the maximum amount of
time within the limits of the protocol definition that the server can
possibly manage to support without turning the problem back on itself.
This is most easily done by using multi-line responses for all errors,
sending the first line after only a very short delay of say 2 to 5
seconds, and then sending each intermediate line, if any, also after
only a short delay, but then waiting at least 60 seconds, but no longer
than 5 minutes (the recommended minimum timeout for the client doing the
waiting for the response), before sending the last line of the response.
This keeps humans doing testing from getting too frustrated, but will
still frustrate the hell out of any client trying to bash away
indiscriminately at your server.
--
Greg A. Woods
+1 416 218-0098; <g.a.woods@???>; <woods@???>
Planix, Inc. <woods@???>; VE3TCP; Secrets of the Weird <woods@???>
