DHCP/NIC IP address contention issues

Thu Apr 26 20:02:29 UTC 2007

On Thursday 26 April 2007, L Goodwin said:
> --- Beech Rintoul <beech at alaskaparadise.com> wrote:
> > > 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: 192.168.1.1
> > > > Name server: (IP address of ISP's name server)
> > > > Configuration for Interface fxp0:
> > > >     IPv4 Address: 192.168.1.33
> > > >     Netmask: 255.255.255.0
> > > >     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...
> >
> > On the XP box what does the output of 'ipconfig
> > /all' tell you about the DHCP lease?
>
> Lease Obtained: Thursday, April 26, 2007 7:36:42 AM
> Lease Expires: Sunday, April 29, 2007 7:36:42 AM
> (also says "Dhcp Enabled: Yes" and "Autoconfiguration
> enabled: Yes")
> Given these settings, I don't think I need to run
> ipconfig /renew on this system...
>
> Note: I wasn't able to get on the Vista box to get
> current ipconfig /all output. An older printout shows
> "DHCP Enabled: No", but it was enabled last time I
> checked. I'll check again.
>
> > On the FreeBSD box what is in /etc/rc.conf?
>
> I had a feeling I'd find something like this, but did
> not know where to look):
> ------------------------------------------------------
> hostname="SERVER" (this is the hostname I want to use)
> ipv6_enable="YES"
> sshd_enable="YES"
> usbd_enable="YES"
> samba_enable="YES"
>
> # -- sysinstall generated deltas --
> # Wed Apr 25 13:38:08 2007
> ifconfig_fxp0="DHCP"
> ipv6_enable="YES"
> hostname="dhcppc0.<ISP's domain name here>"
> ------------------------------------------------------
> Note that there are two each of the ipv6_enable and
> hostname entries.
> I assume I should remove one of each. I want to use
> hostname "SERVER". If I delete this one, will it
> work?:
>   hostname="dhcppc0.<ISP's domain name here>"
> Please advise as to what to change.
>
Delete any duplicates that you don't want. You should only have one 
entry for hostname=, same for ifconfig_fxp0=.

> > 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.
>
> In any case, I verified that it's not installed.
>
> > 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.
>
> Found dbclient.leases.fxp0 containing 2 "lease {...}"
> entries and moved it to $HOME (will delete once it's
> all working).

You don't need to save that. A new one has already been generated. 
Backing up is always a good idea.

>
> I was surprised to find that the entries were for the
> Vista system (not the XP box). I'll verify that DHCP
> is enabled on the Vista box.
>
> One more question: When using DHCP, do I need to do
> anything to enable all hosts on the LAN to know each
> other by hostname (i.e., do I need to add entries to
> /etc/hosts file?)? Once I reboot the FreeBSD box and
> ensure that DHCP is enabled on all hosts, should I be
> able to ping the Windoze systems by hostname (does not
> currently work)?

Adding your machines to /etc/hosts is a good idea, but bear in mind 
since you are using DHCP the IP addresses may change from time to 
time and you will need to correct the file.  

>
> Thanks to Beech and all who responded!
>
>
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-- 
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Beech Rintoul - Port Maintainer - beech at alaskaparadise.com
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