dealing with dictionary attacks

Drew Marshall drew at
Fri Mar 9 23:02:59 CET 2007

On 9 Mar 2007, at 21:44, Steve Campbell wrote:

> How do we deal with dictionary attacks?

With which MTA? Postfix does much of it by default. in_flow_delay is  
one such feature:

# A Postfix process will pause for $in_flow_delay seconds before
# accepting a new message, when the message arrival rate exceeds the
# message delivery rate. With the default 50 SMTP server process
# limit, this limits the mail inflow to 50 messages a second more
# than the number of messages delivered per second.

then you can also play with the smtpd_error limits, both hard and  
soft and tailor those to suit your environment.

Other wise there's always the firewall or the pub either of which can  
provide good short term relief :-)


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