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Date:      Mon, 27 Mar 2000 22:53:09 -0600
From:      "Jim King" <king@sstar.com>
To:        "Cy Schubert - ITSD Open Systems Group" <Cy.Schubert@uumail.gov.bc.ca>, "David Gilbert" <dgilbert@velocet.ca>
Cc:        <freebsd-stable@FreeBSD.ORG>
Subject:   Re: 4.0-STABLE dhcp conflicts. 
Message-ID:  <004f01bf9871$848e7c00$08e48486@marble>
References:  <200003280440.UAA07738@cwsys.cwsent.com>

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On Monday, March 27, 2000 10:40 PM, Cy Schubert - ITSD Open Systems Group
wrote:
> n message <14559.40450.544687.51037@trooper.velocet.net>, David Gilbert
> writes
> :
> > It appears that when I run two (not sure if one does it) tcpdumps on
> > the dhcp server, the dhcp clients don't get any responses to their
> > queries.  Is there some flaw in the dhcpd bpf rules?
>
> I suspect that the dhcp server set the interface to promiscuous mode so
> it can listen for broadcasts.  Tcpdump sets up an interface for
> promiscuous opertion and when you exit tcpdump it returns it to
> non-promiscuous operation.  Killing and restarting your dhcp server
> after exiting tcpdump should solve your problem, as it will set the
> interface up for promiscuous operation again.

I regularly run (and exit) tcpdump and it doesn't affect my DHCP server
(isc-dhcp2).  dhcpd keeps on handing out leases after tcpdump has exited.

syslog has "promiscuous mode enabled" and "promiscuous mode disabled" when I
start and exit tcpdump, which is a bit confusing.  I'm guessing that
promiscuous mode is on the entire time and the messages really mean
something like "promiscuous mode reference count incremented/decremented".

Jim




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