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<div class=Section1>
<p class=MsoPlainText>The following is from someone else’s notes on a talk
given at SIGCOMM08.<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<div style='mso-element:para-border-div;border:solid #E9E4D2 1.0pt;padding:
1.0pt 4.0pt 1.0pt 4.0pt'>
<h3 style='mso-margin-top-alt:12.0pt;margin-right:0in;margin-bottom:4.2pt;
margin-left:0in;line-height:103%;border:none;padding:0in'><span
style='font-family:"Lucida Grande","serif";color:#AA0000'>To Filter or to
Authorize: Network-Layer<span class=apple-converted-space> </span><span
class=twikinewlink><span style='border:solid #CCCCCC 1.0pt;padding:0in'>DoS</span></span><span
class=apple-converted-space> </span>Defense Against Multimillion-node
Botnets<o:p></o:p></span></h3>
</div>
<p style='mso-margin-top-alt:12.0pt;margin-right:0in;margin-bottom:0in;
margin-left:0in;margin-bottom:.0001pt;line-height:13.5pt'><strong><span
style='font-size:10.0pt;font-family:"Lucida Grande","serif";color:black'>Xin
Liu</span></strong><span class=apple-converted-space><span style='font-size:
10.0pt;font-family:"Lucida Grande","serif";color:black'> </span></span><span
style='font-size:10.0pt;font-family:"Lucida Grande","serif";color:black'>(UC
Irvine); Xiaowei Yang (UC Irvine); Yanbin Lu (UC Irvine)<o:p></o:p></span></p>
<p style='mso-margin-top-alt:12.0pt;margin-right:0in;margin-bottom:0in;
margin-left:0in;margin-bottom:.0001pt;line-height:13.5pt'><span
style='font-size:10.0pt;font-family:"Lucida Grande","serif";color:black'>Which
approach works better against flooding DOS attacks from Botnets?<o:p></o:p></span></p>
<ul type=disc>
<li class=MsoNormal style='color:black;mso-margin-top-alt:auto;mso-margin-bottom-alt:
auto;line-height:16.8pt;mso-list:l0 level1 lfo1'><span style='font-size:
10.0pt;font-family:"Lucida Grande","serif"'>filtering-based approaches<o:p></o:p></span></li>
<ul type=circle>
<li class=MsoNormal style='color:black;mso-margin-top-alt:auto;mso-margin-bottom-alt:
auto;line-height:16.8pt;mso-list:l0 level2 lfo1'><span style='font-size:
10.0pt;font-family:"Lucida Grande","serif"'>receiver asks network to
install filters blocking specific traffic<o:p></o:p></span></li>
</ul>
<li class=MsoNormal style='color:black;mso-margin-top-alt:auto;mso-margin-bottom-alt:
auto;line-height:16.8pt;mso-list:l0 level1 lfo1'><span style='font-size:
10.0pt;font-family:"Lucida Grande","serif"'>authorization-based approaches
(capabilities)<o:p></o:p></span></li>
<ul type=circle>
<li class=MsoNormal style='color:black;mso-margin-top-alt:auto;mso-margin-bottom-alt:
auto;line-height:16.8pt;mso-list:l0 level2 lfo1'><span style='font-size:
10.0pt;font-family:"Lucida Grande","serif"'>source requests permission to
send, marks traffic with indication of permission (securely, to some
extent)<o:p></o:p></span></li>
</ul>
</ul>
<p class=MsoNormal style='line-height:13.5pt'><span class=apple-style-span><span
style='font-size:10.0pt;font-family:"Lucida Grande","serif";color:black'>Ongoing
controversy over which approach works best</span><o:p></o:p></span></p>
<p style='mso-margin-top-alt:12.0pt;margin-right:0in;margin-bottom:0in;
margin-left:0in;margin-bottom:.0001pt;line-height:13.5pt'><span
style='font-size:10.0pt;font-family:"Lucida Grande","serif";color:black'>Compared
approaches under various attacks</span><o:p></o:p></p>
<ul type=disc>
<li class=MsoNormal style='color:black;mso-margin-top-alt:auto;mso-margin-bottom-alt:
auto;line-height:16.8pt;mso-list:l1 level1 lfo2'><span style='font-size:
10.0pt;font-family:"Lucida Grande","serif"'>tried to design better
filter-based system, StopIt, to make comparison useful/fair<o:p></o:p></span></li>
</ul>
<p style='mso-margin-top-alt:12.0pt;margin-right:0in;margin-bottom:0in;
margin-left:0in;margin-bottom:.0001pt;line-height:13.5pt'><span
style='font-size:10.0pt;font-family:"Lucida Grande","serif";color:black'>From
their abstract:<span class=apple-converted-space><i> </i></span><i>Our
results show that StopIt outperforms existing filter-based systems, and can
prevent legitimate communications from being disrupted by various<span
class=apple-converted-space> </span><span class=twikinewlink><span
style='border:solid #CCCCCC 1.0pt;padding:0in'>DoS</span></span><span
class=apple-converted-space> </span>flooding attacks. It also outperforms
capability-based systems in most attack scenarios, but a capability-based
system is more effective in a type of attack that the attack traffic does not
reach a victim, but congests a link shared by the victim. These results suggest
that both filters and capabilities are highly effective<span
class=apple-converted-space> </span><span class=twikinewlink><span
style='border:solid #CCCCCC 1.0pt;padding:0in'>DoS</span></span><span
class=apple-converted-space> </span>defense mechanisms, but neither is
more effective than the other in all types of<span class=apple-converted-space> </span><span
class=twikinewlink><span style='border:solid #CCCCCC 1.0pt;padding:0in'>DoS</span></span><span
class=apple-converted-space> </span>attacks.</i><o:p></o:p></span></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>________________________<o:p></o:p></p>
<p class=MsoPlainText>Alan Karp<o:p></o:p></p>
<p class=MsoPlainText>Principal Scientist<o:p></o:p></p>
<p class=MsoPlainText>Virus Safe Computing Initiative<o:p></o:p></p>
<p class=MsoPlainText>Hewlett-Packard Laboratories<o:p></o:p></p>
<p class=MsoPlainText>1501 Page Mill Road<o:p></o:p></p>
<p class=MsoPlainText>Palo Alto, CA 94304<o:p></o:p></p>
<p class=MsoPlainText>(650) 857-3967, fax (650) 857-7029<o:p></o:p></p>
<p class=MsoPlainText>http://www.hpl.hp.com/personal/Alan_Karp<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
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