On 8/21/2014 5:20 AM, Ruud Baart wrote:
> I had a problem with our DNS servers. I turned out that the DNS servers
> were very, very busy with rejecting answers. See discussion "Blocking
> DNS cache queries". I assume DNSAmp is the formal incorporation of the
> solution.
> 

Please give the attached version a try -- any packet that it matches
will also be matched by your 'imperfect' version.

Thanks,
-Tom
-- 
Tom Eastep        \ When I die, I want to go like my Grandfather who
Shoreline,         \ died peacefully in his sleep. Not screaming like
Washington, USA     \ all of the passengers in his car
http://shorewall.net \________________________________________________
#
# Shorewall 4 - DNS Amplification Action
#
#    /usr/share/shorewall/action.DNSAmp
#
#     This program is under GPL 
[http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt]
#
#     (c) 2011,2012 - Tom Eastep ([email protected])
#
#       Complete documentation is available at http://shorewall.net
#
#       This program is free software; you can redistribute it and/or modify
#       it under the terms of Version 2 of the GNU General Public License
#       as published by the Free Software Foundation.
#
#       This program is distributed in the hope that it will be useful,
#       but WITHOUT ANY WARRANTY; without even the implied warranty of
#       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
#       GNU General Public License for more details.
#
#       You should have received a copy of the GNU General Public License
#       along with this program; if not, write to the Free Software
#       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 
02110-1301 USA.
#
#   DNSAmp[([<action>])]
#
#       Default action is DROP
#
##########################################################################################
?format 2

DEFAULTS DROP

IPTABLES(@1)    -       -       udp     53      ; -m u32 --u32 
"0>>22&0x3C\@8&0xffff=0x0100 && 0>>22&0x3C\@12&0xffff0000=0x00010000"

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Description: OpenPGP digital signature

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