<html><head><base href="x-msg://1371/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>Would have to be augmented beyond simple requests as illustrated below to also inspect</div><div>the packet for the mac address. May be direct support in iptables and/or the support modules or could</div><div>ultimately call out to an external program (snarf?).</div><div><br></div><div>Another (1 minute this time) google, not sure about applicability (keywords deep packet inspection)</div><div><a href="http://l7-filter.sourceforge.net/HOWTO">http://l7-filter.sourceforge.net/HOWTO</a></div><div><br></div><br><div><div>On Mar 7, 2012, at 1:19 PM, perl-list wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div><div style="font-family: 'Andale Mono'; font-size: 10pt; color: rgb(0, 0, 0); ">I'm not thinking that would work in the case of a relay agent - These packets would all appear to come from the relay agent and the relay agent would get blocked, not the end-user device.<br><br><div><br></div><hr id="zwchr"><blockquote style="border-left-width: 2px; border-left-style: solid; border-left-color: rgb(16, 16, 255); margin-left: 5px; padding-left: 5px; color: rgb(0, 0, 0); font-weight: normal; font-style: normal; text-decoration: none; font-family: Helvetica, Arial, sans-serif; font-size: 12pt; "><b>From:<span class="Apple-converted-space"> </span></b>"Jeff Waller" <<a href="mailto:jeffw@cnxntech.com">jeffw@cnxntech.com</a>><br><b>To:<span class="Apple-converted-space"> </span></b>"Users of ISC DHCP" <<a href="mailto:dhcp-users@lists.isc.org">dhcp-users@lists.isc.org</a>><br><b>Sent:<span class="Apple-converted-space"> </span></b>Wednesday, March 7, 2012 1:12:39 PM<br><b>Subject:<span class="Apple-converted-space"> </span></b>Re: does isc dhcp 4.2.3 support blocking client which send many<br><br><br>On Mar 7, 2012, at 10:52 AM, Simon Hobson wrote:<br><br>> Martin McCormick wrote:<br>><span class="Apple-converted-space"> </span><br>>> A good mechanism for controlling insane systems<br>>> might be to read time intervals between each MAC address contact<br>>> and start ignorring anybody who has contacted DHCPD more than X<br>>> number of times in X number of seconds.<br>><span class="Apple-converted-space"> </span><br>> Which is the sort of task Logwatch was written for. Anyone know if<span class="Apple-converted-space"> </span><br>> any DHCP filters/actions have been written for it ?<br>><span class="Apple-converted-space"> </span><br>> However, that won't work for devices behind a relay agent. And<span class="Apple-converted-space"> </span><br>> someone said that iptables doesn't work either.<br><br>IP tables can be made to work. Someone is being dumb.<br><br>Here's A link from 5m of google;<br><a href="http://www.wjunction.com/48-technical-security-tutorials/107901-linux-ddos-protection.html">http://www.wjunction.com/48-technical-security-tutorials/107901-linux-ddos-protection.html</a><br><a href="http://www.infond.fr/2010/04/basics-6-tutorial-firewall-iptables.html">http://www.infond.fr/2010/04/basics-6-tutorial-firewall-iptables.html</a><br><br>Form the 2nd source, seems approximately the same;<br><br>#9 allow 5 TCP connexion attempts<span class="Apple-converted-space"> </span><br># with 2 per minuts frequency<br>#iptables -A INPUT -m state --state NEW -m recent --set<br>#iptables -A INPUT -m state --state NEW -m recent --update --hitcount 6 -j DROP<br>#iptables -A INPUT -m state --state NEW -m recent --update --seconds 60 --hitcount 3 -j DROP<br><br>><span class="Apple-converted-space"> </span><br>> --<span class="Apple-converted-space"> </span><br>> Simon Hobson<br>><span class="Apple-converted-space"> </span><br>> Visit<span class="Apple-converted-space"> </span><a href="http://www.magpiesnestpublishing.co.uk/">http://www.magpiesnestpublishing.co.uk/</a><span class="Apple-converted-space"> </span>for books by acclaimed<br>> author Gladys Hobson. Novels - poetry - short stories - ideal as<br>> Christmas stocking fillers. Some available as e-books.<br>> _______________________________________________<br>> dhcp-users mailing list<br>><span class="Apple-converted-space"> </span><a href="mailto:dhcp-users@lists.isc.org">dhcp-users@lists.isc.org</a><br>><span class="Apple-converted-space"> </span><a href="https://lists.isc.org/mailman/listinfo/dhcp-users">https://lists.isc.org/mailman/listinfo/dhcp-users</a><br><br>_______________________________________________<br>dhcp-users mailing list<br><a href="mailto:dhcp-users@lists.isc.org">dhcp-users@lists.isc.org</a><br><a href="https://lists.isc.org/mailman/listinfo/dhcp-users">https://lists.isc.org/mailman/listinfo/dhcp-users</a><br><br></blockquote><br></div>_______________________________________________<br>dhcp-users mailing list<br><a href="mailto:dhcp-users@lists.isc.org">dhcp-users@lists.isc.org</a><br><a href="https://lists.isc.org/mailman/listinfo/dhcp-users">https://lists.isc.org/mailman/listinfo/dhcp-users</a></div></blockquote></div><br></body></html>