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Date:      Fri, 19 Oct 2001 14:52:46 +0200
From:      "Jose M. Alcaide" <jose@we.lc.ehu.es>
To:        Harti Brandt <brandt@fokus.gmd.de>
Cc:        Terry Lambert <tlambert2@mindspring.com>, Beech Rintoul <akbeech@anchoragerescue.org>, current@FreeBSD.ORG, net@FreeBSD.ORG
Subject:   Re: arp: <some ether addr> is using my IP address 0.0.0.0!  ??!?!?
Message-ID:  <20011019145246.D327@v-ger.we.lc.ehu.es>
In-Reply-To: <20011019110116.Y1072-100000@beagle.fokus.gmd.de>; from brandt@fokus.gmd.de on Fri, Oct 19, 2001 at 11:12:48AM %2B0200
References:  <3BCEEBDD.46121235@mindspring.com> <20011019110116.Y1072-100000@beagle.fokus.gmd.de>

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On Fri, Oct 19, 2001 at 11:12:48AM +0200, Harti Brandt wrote:
> I have run tcpdump all night to find out what happens. The host receives
> an ARP request with a source address of 0.0.0.0:
> 
> 18:33:51.222688 arp who-has hydra tell 0.0.0.0
>                          0001 0800 0604 0001 0030 65c6 a174 0000
>                          0000 0000 0000 0000 c1af 8755 5555 5555
>                          5555 5555 5555 5555 5555 5555 5555
> 
> I think, this may happen if the host does not yet know it's IP address
> (DHCP maybe?).
> 
> But FreeBSD-current for some unknown reason answers to this request:
> 
> 18:33:51.222835 arp reply 0.0.0.0 is-at 0:60:97:a:99:f
>                          0001 0800 0604 0002 0060 970a 990f 0000
>                          0000 0030 65c6 a174 0000 0000 5555 5555
>                          5555 5555 5555 5555 5555 5555 5555
> 
> and then prints:
> 
> Oct 18 18:33:51 scotty /boot/kernel/kernel: arp: 00:30:65:c6:a1:74 is using my IP address 0.0.0.0!

Same here. My -CURRENT system is replying to those ARP request which carry
0.0.0.0 as sender IP address:

14:43:33.706099 arp who-has 158.227.48.193 (ff:ff:ff:ff:ff:ff) tell 0.0.0.0
14:43:33.706152 arp reply 0.0.0.0 is-at 0:d0:b7:3e:a0:fb

> I think this is because I have an interface that is up and has NO IP
> address:

I don't think so:

# ifconfig -a
fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet 158.227.6.52 netmask 0xffffff00 broadcast 158.227.6.255
        inet6 fe80::2d0:b7ff:fe3e:a0fb%fxp0 prefixlen 64 scopeid 0x1 
        inet6 fec0::9ee3:634 prefixlen 120 
        ether 00:d0:b7:3e:a0:fb 
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
        inet6 ::1 prefixlen 128 
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2 
        inet 127.0.0.1 netmask 0xff000000 

Something is broken in the ARP implementation of -CURRENT.

  --JMA
-- 
****** Jose M. Alcaide  //  jose@we.lc.ehu.es  //  jmas@FreeBSD.org ******
** "Beware of Programmers who carry screwdrivers" --  Leonard Brandwein **

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