So I guess I'll re-ask the question here: According to
https://tools.ietf.org/html/rfc1122 that RFC has been updated quite a
bit over the last 23 years. Have you followed that chain upwards to make
sure that your concerns are still valid?
Doug
On 3/9/2012 3:26 PM, Alex Yong wrote:
> (Originally posted on freebsd-hackers@ - sorry)
>
> Hi all,
>
> I've been playing around with IPv6 networking on FreeBSD release 8.2 and
> found that there seems to be no strong incoming host model as specified in
> RFC 1122.
>
> I've spotted that in IPv4 there is the sysctl "net.inet.ip.check_interface"
> which defaults to set, but I've been unable to find any guarantees that
> strong host model is enforced in v6 in the comments or internet. According
> to the IPv6 Core Protocols Implementation book (3.7 "Input processing:
> ip6_input() Function") the incoming network packet processing in ip6_input
> should use the routing table to look up whether packets are of relevance
> for an interface - but the code base has diverged significantly since then
> including vnets for jails which makes me wonder if this is a bug. However
> before going into the long grass and trying to fix it I thought I'd ask
> here to see if there's anything I could try first, if I'm making some
> horrific mistakes, or if somebody had come across this already (I had a
> quick look at svn but didn't see anything of concern).
>
> My recipe for reproducing is thus:
>
> One FreeBSD 8.2 machine (the box under test), with 2 network interfaces
> (interface 0 and interface 1). interface 0 is connected to a subnet with
> routes to the outside world on v4 and v6. Interface 1 is connected
> directly via ethernet cable to the interface of a testing machine, with v4
> disabled and a static v6 address for an unroutable subnet via the other
> interface. A route is configured for this subnet out of interface 1 (to
> allow for communications with the testing machine).
>
> The testing machine (which happens to be running FreeBSD) has 2 network
> interfaces (interface A and B). Interface A is connected to the same
> subnet as interface 0 (this is for my administration prodding of the
> testing device), and interface B is directly connected to interface 1 on
> the machine under test. Interface B has a staticly configured IPv6 address
> that matches the subnet of interface 1. It has a route to allow traffic to
> flow this way, *and* a route configured to route traffic for the box under
> tests interface 0 IPv6 address via interface B.
>
> If I ping interface 0 from box 1, I get a response. To prove that the
> response isn't coming in via the other links I used tcpdump on that
> interface on the testing machine *and* the machine under test and showed
> packets entering and responses leaving those interfaces. My expectation
> here would be to see packets entering (as the bpf hook is below the IP
> layer) but see no response.
>
> I checked sysctl net.inet6.ip6.forwarding is set to 0 (on both machines).
>
> Many thanks for any help
>
> AlexY
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