Messages in this thread | | | Date | Thu, 23 Sep 1999 17:02:54 -0600 | From | Galen Hazelwood <> | Subject | Headerless packets hitting ethernet? |
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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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