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Date:      Tue, 10 Apr 2007 21:06:13 +0100
From:      RW <fbsd06@mlists.homeunix.com>
To:        freebsd-questions@freebsd.org
Subject:   Re: ipfilter and DHCP
Message-ID:  <20070410210613.6af9b48c@gumby.homeunix.com>
In-Reply-To: <44mz1gqbdf.fsf@be-well.ilk.org>
References:  <200704101334.l3ADY1MJ006807@shadow.sixcompanies.com> <44mz1gqbdf.fsf@be-well.ilk.org>

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On Tue, 10 Apr 2007 15:26:36 -0400
Lowell Gilbert <freebsd-questions-local@be-well.ilk.org> wrote:

> "J.D. Bronson" <jbronson-freebsd@sixcompanies.com> writes:
> 
> > Ok...what do you guys do to handle a change of IP/network via DHCP
> > with ipfilter?
> >
> > I have been told that if my IP changes while the machine is up and
> > running that ipfilter WON'T see this change and needs to be
> > told...supposedly it only reads the IP when it starts itself.
> >
> > If this is true, is there any easy way to fix this?
> > I run ipcheck.py and that can invoke a script if needed if it
> > notices and IP changed....
> >
> > ipnat.conf:
> > map bge1 192.43.82.0/24 -> 0/32 proxy port ftp ftp/tcp
> > map bge1 192.43.82.0/24 -> 0/32 portmap tcp/udp auto
> > map bge1 192.43.82.0/24 -> 0/32
> >
> > rdr bge1 0.0.0.0/0 port 25 -> 192.43.82.170 port 25
> >
> >
> > I presume if it reads the IP and fills in the '0/32' + '0.0.0.0/0'
> > values at startup...having my IP change could be disasterous.
> 
> When your IP changes, you can have dhclient trigger a script of your
> choosing.  You can use that to alter your firewall rules.

Does it matter though?

# rcorder /etc/rc.d/* |egrep  "ipfil|dhc"
/etc/rc.d/ipfilter
/etc/rc.d/dhclient

ipfilter doesn't actually have an ip address for the interface when it
starts up, so it seem unlikely it can't cope with a new address.

It wouldn't hurt to do an "/etc/rc.d/ipfilter resync" though



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