Re: mboned: UDP port conflict mtrace/traceroute

On Fri, Jul 26, 2019 at 4:26 PM Joe Touch <[email protected]> wrote:
>
>
>
> On Jul 26, 2019, at 12:11 PM, James A. (Jim) Stevens <[email protected]> wrote:
>
> !   Why wouldn't the IP ID be equally "safe"? (you can set this even for
> !   IPv6 that aren't fragments). You're supposed to get the Internet header
> !   back...
> !
> !   > Ultimately, we should ask for IANA to put for the 254 port numbers
> !   > following the traceroute assigned port number something like
> !   > "reserved for tracroute", and maybe someone who wants an easy RFC
> !   > number could write a one-pager outlining this scheme informationally ;-)]
> !
>

Just FYI, I sent email to IANA letting them know that ports 33435 -
33534 should probably be listed it as "Known Unauthorized Use".
>From some archaeology, 33434 is apparently 2^15 + 666, and the
"standard" traceroutes use up to 100 ports.
I based this on the Van Jacobson ([email protected]) - 1988 which he
"stole" (credited) from Steve Deering -- easiest location of code is:
https://github.com/freebsd/freebsd/blob/master/contrib/traceroute/traceroute.c

I don't much like referring to it as "Known Unauthorized Use" but
that's technically what it is -- the important bit to me seems to be
that we make in some way so they don't get handed out, exactly what
they should be called is a less pressing problem.

W

> RFC 6864 specifically mentions this use in 3.1 and recommends against it.  In particular, the RFC deprecates all uses of the IP ID field other than for reassembly.
>
>
> At the network layer, yes. But this would be at other layers AND only when the value could be set.
>
> Regardless, the rest of the returned packet ought to be enough. It’s 8 bytes after IP, which means things like multiple source ports or even different UDP checksums provide sufficient differences for multiple concurrent probes.
>
> Joe
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--
I don't think the execution is relevant when it was obviously a bad
idea in the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair
of pants.
   ---maf

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