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SubjectHeaderless packets hitting ethernet?
Greetings, oh mighty hackers.

I've made an interesting and very annoying discovery. In some
circumstances, packets are going out on the wire which seem to be
completely missing the ethernet header. A wire sniffer saw packets which
started immediately with an IP header instead.

The problem is one we'd never have noticed if we hadn't tried to run
this system on a cable modem. The modem scans the first packet it sees,
grabs the MAC address, and won't let go unless you reset it. Of course,
if there's no ethernet header, what it thinks is the MAC address is
entirely bogus, and will totally ignore any further legitimate packets
coming from that ethernet card.

These packets show up most reliably when I'm running a DHCP client on
the interface. If I assign it a static address, one or two show up, but
not until after at least one legitimate packet goes through, so no harm
is done. I suspect that fact the interface is not really completely
configured has something to do with this.

The system is currently running a heavily patched 2.0.36 (i.e., not
quite 2.0.38). I'm currently trying other kernel versions to see if they
have the same problem. Although with such scanty information I know not
to expect a solution from anyone, what I really want to know is: does
this seem even remotely familiar to anyone? Are we the only people
who've seen this problem?

It seems quite possible that nobody has noticed this but us. Most
ethernet devices would just ignore these headerless packets. But hope
springs eternal.

Thanks in advance,
--Galen Hazelwood

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