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Date:      Tue, 24 May 2011 16:42:23 -0400
From:      Greg Larkin <glarkin@FreeBSD.org>
To:        Andy Wodfer <wodfer@gmail.com>
Cc:        freebsd-questions <freebsd-questions@freebsd.org>
Subject:   Re: Urgent: Under attack - need tcpdrop help
Message-ID:  <4DDC182F.1090404@FreeBSD.org>
In-Reply-To: <BANLkTikGjnh-cfO_dtk=jf6ZVNiY=x8nqw@mail.gmail.com>
References:  <BANLkTikGjnh-cfO_dtk=jf6ZVNiY=x8nqw@mail.gmail.com>

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On 5/24/11 4:29 PM, Andy Wodfer wrote:
> Hi,
> One of my FreeBSD servers is currently being attacked (DDOS) and I'm
> blocking IP addresses in my firewall. However, there are a large number of
> hung tcp connections and I want them gone.
> 
> Can anyone help me with a script (command line) that can read a netstat -n
> and tcpdrop all IP addresses that has more than 10 connections or a more
> manual command where I can input an IP and it will drop all connections from
> that IP regardless of port?
> 
> Thanks in advance!
> 
> Shell scripting isn't what I'm best at unfortunatly ...
> 
> Andy

Hi Andy,

This will drop all connections to/from IP address 192.168.22.22:

tcpdrop -l -a | grep 192.168.22.22 | sh

Just substitute your desired IP address, and that will do the trick.

Good luck,
Greg
- -- 
Greg Larkin

http://www.FreeBSD.org/           - The Power To Serve
http://www.sourcehosting.net/     - Ready. Set. Code.
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