On 8/2/12 1:19 AM, Øyvind Lode - Forums wrote:
> 
> From: Tom Eastep [mailto:[email protected]] 
> Sent: 2. august 2012 04:32
> On 8/1/12 3:24 PM, Bill Shirley wrote:
>> If I understand this correctly, some device on your LAN is sending 
>> packets with a source address of 127.0.0.1.  I would want to see those 
>> packets with tcpdump:
>>
>> tcpdump -n -i eth1 host 127.0.0.1
>>
> 
>> I would also want to see the ethernet header on the offending packets, so I 
>> would add the -e option:
> 
>> tcpdump -nei eth1 host 127.0.0.1
> 
> munin:~# tcpdump -nei eth1 host 127.0.0.1
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes
> 10:04:28.383784 00:19:cb:c2:20:e7 > ff:ff:ff:ff:ff:ff, ethertype ARP 
> (0x0806), l
> ength 60: Request who-has 192.168.1.5 tell 127.0.0.1, length 46
> 10:05:28.384162 00:19:cb:c2:20:e7 > ff:ff:ff:ff:ff:ff, ethertype ARP 
> (0x0806), l
> ength 60: Request who-has 192.168.1.5 tell 127.0.0.1, length 46
> 10:06:28.384288 00:19:cb:c2:20:e7 > ff:ff:ff:ff:ff:ff, ethertype ARP 
> (0x0806), l
> ength 60: Request who-has 192.168.1.5 tell 127.0.0.1, length 46
> 10:07:28.384566 00:19:cb:c2:20:e7 > ff:ff:ff:ff:ff:ff, ethertype ARP 
> (0x0806), l
> ength 60: Request who-has 192.168.1.5 tell 127.0.0.1, length 46
> 10:08:28.565055 00:19:cb:c2:20:e7 > ff:ff:ff:ff:ff:ff, ethertype ARP 
> (0x0806), l
> ength 60: Request who-has 192.168.1.5 tell 127.0.0.1, length 46
> 
> __________
> 
> I hope you guys understand the above output.
> Because I don't fully understand :)

The above shows that the system with MAC address 00:19:cb:c2:20:e7 wants
to communicate with 192.168.1.5 but it is bizarrely using 127.0.0.1 as
the source IP address in its ARP requests. So whichever box has that MAC
address is the problem.

-Tom
-- 
Tom Eastep        \ When I die, I want to go like my Grandfather who
Shoreline,         \ died peacefully in his sleep. Not screaming like
Washington, USA     \ all of the passengers in his car
http://shorewall.net \________________________________________________

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