DHCP/NIC IP address contention issues

Beech Rintoul beech at alaskaparadise.com
Thu Apr 26 07:10:51 UTC 2007

> Beech Rintoul <beech at alaskaparadise.com> wrote: On Wednesday 25 
April 2007, L Goodwin said:
> > Will someone please lead me in the right direction towards
> > resolving the following network issue?
> >
> > I just added a FreeBSD server to a LAN that consists of a router
> > and 2 pc's, one of which is running Windows XP Pro and the other
> > Windows Vista. The lan is connected to the Internet via a cable
> > modem that goes through the router. The router is set up to be
> > the DHCP server. Now it is being assigned a non-unique IP
> > address.
> >
> >  Before adding the FreeBSD box to the mix, everybody was getting
> > along fine (unique IP addresses were dynamically assigned to the
> > pc's).
> >
> > I connected the FreeBSD box to the router, selected "Configure
> > additional network interfaces" from the sysinstall menu, selected
> > "fxp0 Intel EtherExpress Pro/100B PCI Fast Ethernet card" from
> > the top of the list and clicked "OK" to prompts to try to
> > configure IPv6 and DCHP. When done, the Network Configuration
> > dialog contained the following values (which I did not alter):
> >
> > Host: dhcppc0
> > Domain: (the cable provider's domain name)
> > IPv4 Gateway:
> > Name server: (IP address of ISP's name server)
> > Configuration for Interface fxp0:
> >     IPv4 Address:
> >     Netmask:
> >     Extra options: (blank)
> >
> > Note that the Host field does not match the hostname of the
> > FreeBSD box, which is named "SERVER" (real creative, huh?). I
> > guess I should have changed the Host field to "SERVER", eh?
> >
> > Then I got the following console messages on the FreeBSD server:
> >
> > 1) "Apr 25 13:33:19 SERVER kernel: arp 00:40:f4:47:fb:8e is using
> > my IP address xxx.xxx.x.xx!" 2) "dhcppc0# Apr 25 14:07:05 dhcpp0
> > kernel: arp: 00:40:f4:47:fb:8e is using my IP address
> > xxx.xxx.x.xx!"
> >
> > I ran "ipconfig /all" on both Windows boxes and found that the
> > FreeBSD box is assigned the same IP address as the Windows XP box
> > (which had that IP address FIRST). Why is the FreeBSD box being
> > assigned a non-unique IP address?
> 1. Check that your router's dhcp server is set up properly.
> 2. Check that the windows box is not set up with a static ip. The
> box could be hard coded to an ip address and your dhcp server
> thinks the lease is free.
> Other than that you need to supply more info.
> Beech

> On Wednesday 25 April 2007, L Goodwin said:
> I'll double-check the things you listed. If you can tell me what
> additional info I need to supply and where to get it, I'll be happy
> to oblige. Thanks...

First off, please don't top post. It makes the conversation hard to 

On the XP box what does the output of 'ipconfig /all' tell you about 
the DHCP lease?

On the FreeBSD box what is in /etc/rc.conf?

On your router what is the DHCP range set to? and how long do the 
leases last before they expire?

And from the other post it's not possible to "accidentally" make the 
FreeBSD box a DHCP server. You would have to install the isc-dhcpd 
port, then configure and start it.

If all of the above looks ok, go to /var/db and delete anything that 
says "dhclient.leases" then restart your machine and see if you get a 
new IP.


Beech Rintoul - Port Maintainer - beech at alaskaparadise.com
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