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 From:  "Wilson, Ron" <rwilson at mpr dot com>
 To:  <m0n0wall at lists dot m0n0 dot ch>
 Subject:  dhcp on opt1 - repeated leases + stopped leases
 Date:  Thu, 18 Jan 2007 13:30:24 -0500
I just installed my first m0n0wall this weekend.  Everything seems to be
working great, but I've run into a problem with my OPT1 DHCP connection.
I've searched the mailing list archive and I don't see any solutions to
the problem I will describe below.  Here is my config:

Cable Modem > WAN > LAN/OPT1/OPT2

LAN is on 192.168.1.1/24 -> linksys router -> winxp box + laser printer
+ wireless
OPT1 is on 192.168.2.0/24 -> netgear switch -> win2k box
OPT2 is on 192.168.3.0/24 -> unused

DHCP is enabled on all three subnets.  NAT is enabled on LAN and OPT1 to
bring in a few ports for VNC, TELNET, etc.  The appropriate rules are
defined.  There is no DMZ or any rules to separate any of the subnets
from each other - just the NAT and supporting rules.

On LAN, everything has worked flawlessly.  I even set up some reserved
IPs in the DHCP.  (Speaking of which, why don't the reserved DHCP IPs
show up in the active DHCP lease table?  They are still being leased,
aren't they?  I was under the impression that this would be the case.)

On OPT1, I find that the DHCP server fails.  At first, I thought it was
failing after 2 hours, i.e. 7200 seconds.  However the timing is not
consistent with the lease time.  I discovered that the PC on OPT1 would
become unreachable after a random period of time, usually a matter of
hours, sometimes 2 or 3 hours, sometimes 8 or 12.  When I say
unreachable - I mean both inside and outside the network.  I checked the
PC itself and it is not crashed or locked up.  When I looked at the
active leases, there would be no lease for that box.  So, I monitored
the box hourly to see if I could catch the moment that the lease failed.
I got lucky.  The link below shows a screen capture from the active
lease display.  Basically, the firewall makes tons of leases and some
only last half a second before they expire.  I think it does this
constantly for a period of time before the monowall decides it has had
enough and just stops serving leases on OPT1 altogether.

http://www.thereverend.org/images/mono_dhcp_opt1.gif

Any ideas?

Ron Wilson

-----------------------------------------
Ron Wilson, Senior Engineer, 518.831.7546
MPR Associates         http://www.mpr.com
-----------------------------------------

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