<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">My 2 cents on the discussion:<div class=""><br class=""></div><div class="">I agree that the network should take countermeasures to mitigate Interest flooding attacks and I believe that what you gain from the PIT state is more than the price that you have to pay.</div><div class=""><br class=""></div><div class="">If the flooding concerns have to do with PIT, then the PIT size of each router should be limited. If the size reaches the maximum, the router should start dropping state in the sense of erasing PIT entries to mitigate a potential flooding attack. Which entries a router should erase? Probably, the ones closer to expiration.</div><div class=""><br class=""></div><div class="">How exactly to do that is an open question, but this is my rough intuition.</div><div class=""><br class=""><div class="">
<div class=""><div class=""><div class=""><span class="" style="float: none; display: inline !important;">Spyridon (Spyros) Mastorakis</span><br class=""><span class="" style="float: none; display: inline !important;">Personal Website: </span><a href="http://cs.ucla.edu/~mastorakis/" class="">http://cs.ucla.edu/~mastorakis/</a><br class=""><span class="" style="float: none; display: inline !important;">Internet Research Laboratory</span><br class=""><span class="" style="float: none; display: inline !important;">Computer Science Department</span><br class=""><span class="" style="float: none; display: inline !important;">UCLA</span></div><div class=""><br class=""></div></div></div></div><div><blockquote type="cite" class=""><div class="">On Sep 27, 2016, at 3:59 PM, <a href="mailto:woodc1@uci.edu" class="">woodc1@uci.edu</a> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">On September 27, 2016 at 3:23:14 PM, Lixia Zhang (<a href="mailto:lixia@cs.ucla.edu" class="">lixia@cs.ucla.edu</a>) wrote:<br class=""><blockquote type="cite" class=""><br class=""><blockquote type="cite" class="">On Sep 27, 2016, at 1:49 PM, Cesar Ghali wrote:<br class=""><br class="">The PIT may very well serve a useful purpose in NDN/CCN. However, it creates well-known<br class=""></blockquote>security problems (interest flooding is trivial) and it’s highly doubtful that a deterministic<br class="">solution is possible.<br class=""><br class="">the discussion below is on how to effectively mitigate Interest flooding.<br class="">By removing PIT, one also removes a number of important functions enabled by PIT.<br class=""></blockquote><br class="">To re-iterate Cesar’s point, as of now, there is no truly effective<br class="">interest flooding mitigation. However, one concrete way to minimize<br class="">the attack surface (for routers) is to get rid of the attack's root<br class="">cause: the PIT. (Producers could still be hosed with bogus interests.)<br class="">And since the PIT enables several important functions, other<br class="">architecture changes will probably have to follow in its wake.<br class=""><br class="">Personally, I don’t think we should settle with an architectural<br class="">element that has a known (and quite severe) weakness simply because it<br class="">enables some nice features in practice. The more serious design<br class="">problems must be dealt with first, not last.<br class=""><br class="">Chris<br class=""></div></div></blockquote></div><br class=""></div></body></html>