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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1F497D'>We have a Moto BSR64000, and I’ve never seen any DHCP rate-limiting, either. Just a “max-hosts”.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1F497D'>Frank<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><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+frnkblk=iname.com@lists.isc.org [mailto:dhcp-users-bounces+frnkblk=iname.com@lists.isc.org] <b>On Behalf Of </b>"Daniel D. Gonçalves"<br><b>Sent:</b> Wednesday, July 14, 2010 12:29 PM<br><b>To:</b> Patricio Latini<br><b>Cc:</b> dhcp-users@isc.org<br><b>Subject:</b> Re: DISCOVERY STORM DoS ?<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>My CMTS is a Cisco UBR 10K, but I didn't found information about rate limit.<br> <br>Patricio Latini escreveu: <o:p></o:p></p><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</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Patricio</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><div><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0in 0in 0in;border-color:-moz-use-text-color -moz-use-text-color'><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'> <a href="mailto:dhcp-users-bounces+p_latini=hotmail.com@lists.isc.org">dhcp-users-bounces+p_latini=hotmail.com@lists.isc.org</a> [<a href="mailto:dhcp-users-bounces+p_latini=hotmail.com@lists.isc.org">mailto:dhcp-users-bounces+p_latini=hotmail.com@lists.isc.org</a>] <b>On Behalf Of </b>"Daniel D. Gonçalves"<br><b>Sent:</b> Monday, July 12, 2010 5:39 PM<br><b>To:</b> <a href="mailto:dhcp-users@isc.org">dhcp-users@isc.org</a><br><b>Subject:</b> DISCOVERY STORM DoS ?</span><o:p></o:p></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>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><p class=MsoNormal><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><p class=MsoNormal><o:p> </o:p></p></div></body></html>