[Mimedefang] Blocking Dictionary Attacks

[Matt Garretson]

Petra Humann wrote:
> Do you know the sendmail badrcpt_shutdown patch?
> http://www.jmaimon.com/sendmail/
> 
> After an defined number of bad recipients the SMTP session terminates:
> "Possible SMTP RCPT flood, shutting down connection."


I hadn't heard about that patch.  But even without the patch,
you can do basically the same things.  I have this in my 
sendmail.mc:

define(`confBAD_RCPT_THROTTLE',`5')dnl

[...]

LOCAL_RULESETS
Scheck_data
# Reject if lots of bad addresses:
R $*            $: $&{nbadrcpts}
R $+            $: $(arith l $@ $1 $@ 8 $)
R FALSE         $# error $@ 5.1.2 $: "553 Too many bad recipients"


I guess this is getting a bit off-topic, though.

-Matt