how to fight concurrent connection DOS attack to FreeBSD ftpd?

JD Bronson jbronson at
Sat Nov 24 07:49:27 PST 2007

At 10:34 PM 11/24/2007 +0800, Zhang Weiwu wrote:
>Dear all
>I run a ftp site which is being attacked by someone who issue some 1000
>concurrent connection for downloading as anonymous. How can I fight back?

how about controlling access via pf?
you can limit the number of connections from the SAME IP and/or
number of connections from the SAME IP over a given time...

Or just block the IP and be done with it?

We use this method for controlling attacks on SSH port 22 but it 
could also be used for any type of needed control.

the items of value under pf are:
flush global



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