Re: mboned: UDP port conflict mtrace/traceroute

> 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 ;-)]
> !
> 
> 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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