Re: Have I misunderstood an ipchains concept?
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On Thu, 21 Sep 2000, Christian Pernegger wrote:
> > What they are saying is that a machine *should* never recieve a packet that
> > has originated from outside the machine, yet claims (by way of the source
> > IP) to have originated from that machine?
>
> Exactly. A packet arriving on an eth interface comes from outside.
> I always thought that a packet destined to the host itself would
> arrive on the loopback interface, no matter what.
Volume 1 of Rich Stevens' TCP/IP Illustrated indicates that your thinking
is correct. It's in section 2.7, where the book discusses the loopback
interface. I'll quote from the book for bit here:
___
Datagrams sent to a broadcast address or a multicast addresss are copied
to the loopback interface and sent out on the Ethernet. This is because
the definition of broadcasting and multicasting includes the sending host.
- ---
So, were we to take the Stevens book as gospel, then it seems like Linux
is doing something wrong here. I don't know if this is documented
anywhere or not.
noah
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