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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Daniel, you should activate dhcp throttling in your CMTS. Advanced
CMTSs support rate limiting features that limit the quantity of DHCP
DISCOVERS/REQUESTSs in order to avoid this kind of DoS attacks<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Patricio<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";
color:windowtext'>From:</span></b><span style='font-size:10.0pt;font-family:
"Tahoma","sans-serif";color:windowtext'>
dhcp-users-bounces+p_latini=hotmail.com@lists.isc.org
[mailto:dhcp-users-bounces+p_latini=hotmail.com@lists.isc.org] <b>On Behalf Of </b>"Daniel
D. Gonçalves"<br>
<b>Sent:</b> Monday, July 12, 2010 5:39 PM<br>
<b>To:</b> dhcp-users@isc.org<br>
<b>Subject:</b> DISCOVERY STORM DoS ?<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span class=longtext><span style='background:white'>I'm
having the following problem, a client begins randomly sending a storm of
requests DISCOVERY, and DHCP responds with a OFFER, but </span></span><span
class=longtext>nothing more than that<span style='background:white'>. </span>These
requests cause denial of service on DHCP. <span style='background:white'>Even
removing the MAC from DHCP, the DISCOVERY continuing.</span></span><span
class=shorttext><span style='background:white'> I tried these versions </span></span>V3.1.1
and 4.1.1-P1<span class=shorttext><span style='background:white'>, both have
the same problem. </span></span><span style='background:white'><br>
<span class=shorttext>The IP 10.40.0.1 is a Cisco CMTS with dhcp relay
activated.</span></span><br>
<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPOFFER on 200.XX.XX.XX to 08:10:74:33:3a:af
(Router) via 10.14.0.1<br>
Jul 12 12:03:03 gw dhcpd: DHCPDISCOVER from 08:10:74:33:3a:af (Router) via
10.14.0.1<br>
<br>
Thanks.<br>
<br>
Daniel<br>
<br>
<br>
<br>
__________ Information from ESET Smart Security, version of virus signature
database 5267 (20100710) __________<br>
<br>
The message was checked by ESET Smart Security.<br>
<br>
<a href="http://www.eset.com">http://www.eset.com</a><o:p></o:p></p>
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<BR><BR>__________ Information from ESET Smart Security, version of virus signature database 5267 (20100710) __________<BR><BR>The message was checked by ESET Smart Security.<BR><BR><A HREF="http://www.eset.com">http://www.eset.com</A><BR> </body>
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