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Rune Kock wrote:
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<pre wrap="">---------- Forwarded message ----------
From: Rune Kock <a class="moz-txt-link-rfc2396E" href="mailto:rune.kock@gmail.com"><rune.kock@gmail.com></a>
Date: Thu, Aug 21, 2008 at 20:03
Subject: Re: [Dnsmasq-discuss] Request for brain-storm: Rogue
dhcp-servers on the lan
To: Paul Chambers <a class="moz-txt-link-rfc2396E" href="mailto:bod@bod.org"><bod@bod.org></a>
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<pre wrap="">So, you're saying that this Powerconnect 2716 is able to tell me on
which port a given MAC communicates?
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<pre wrap="">I can't say for certain, having not tried it myself. What I do know is the
documentation claims it supports the RMON MIB of SNMP, and there's an
optional group in that MIB specification that's described as:
<snip>
Since it's optional, I don't know if the Powerconnect switches exposes this
info or not. I don't use SNMP at home, so I'd have to install an SNMP
browser and take a look. It may be a few days before I have time to do that.
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<pre wrap=""><!---->Please do.
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Sadly the Dell Powerconnect 2716 does not support SNMP at all. The
so-called 'RMON' support is limited to aggregated statistics for the
entire switch, and is only visible within the web interface, not
through SNMP (I think it's very misleading on Dell's part to call that
RMON, to be honest).<br>
<br>
So no joy with this particular model, sorry. It's possible that there
are other mid-level switches which do support this info via SNMP, but I
have no information to offer.<br>
<br>
Another random idea: how about attempting to 'starve' a rogue DHCP
server of addresses to hand out? i.e. monitor for another DHCP server,
and if one appears, repeatedly request fresh DHCP addresses until it
has no more to hand out? would the requests need to come from unique
MAC addresses? does it help to pretend to be a bootp relay? This isn't
an area I know a whole lot about, to be honest.<br>
<br>
It's a shame DHCP doesn't offer a mechanism to handle such situations
more gracefully. I guess we could always extend dnsmasq to add one, in
an attempt to establish a de facto standard :)<br>
<br>
-- Paul<br>
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