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.
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