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 From:  Justin Ellison <justin at techadvise dot com>
 Cc:  m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] DHCP server - static clients only
 Date:  Thu, 24 Jun 2004 14:49:38 -0500
On Thu, 2004-06-24 at 14:26, Adam Nellemann wrote:
> > On Thu, 24 Jun 2004, Adam Nellemann wrote:
> > 
> > It insures that existing access isn't killed by the loss of the lease.  
> > Without persistent mappings, the reincarnated server may reassign an
> > address to a different client, resulting in two clients with the same
> > address.

ISC DHCPd does issue a ping to the IP before issuing a lease - so
realistically, this could only happen if the hosts on the LAN were
blocking pings.

The problem is that dhcp is supposed to re-offer the same IP over and
over to an existing MAC.  This is what's being lost in a reboot of
m0n0wall.  There aren't any quick and easy hooks in the DHCPd to execute
a script upon a lease (that I know of), so more than likely the better
solution would be to have a PHP script run via cron, and parse
dhcpd.log.  Any new mappings that weren't present before could be stored
in config.xml.  Upon bootup, we could build a quick dhcpd.leases file
from those entries.  Given the excellent uptime of most m0n0walls, the
script probably wouldn't need to be ran that often.

I may dig into this a little deeper and see what can be done.


Justin Ellison <justin at techadvise dot com>
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