Re: mapping ICMP codes to Unix errno code numbers

[Darren Reed <darrenr%netbsd.org@localhost>]

On 26/03/2013 5:46 AM, Erik E. Fair wrote:
> I just filed PR kern/47693 which deals with an immediate deficiency
> in our ICMP handling - we don't handle unreachable code 13 valid
> code as valid. That needs to be fixed ASAP, and the patch pulled
> up to both netbsd-6 and netbsd-5.
>
> However, there's an additional semantic issue for programmers: I
> believe Unix needs an additional errno code to indicate "remote
> permission denied" as distinct from "connection refused" (daemon's
> not listening on that port). There are multiple ICMP unreachable
> codes which make this semantic error distinction.
>

Erik,

How do you know that the administratively prohibited ICMP error
will 100% of the time come from a remote network?

Afterall, it could also be generated by your local firewall or perhaps
even the host itself!

Kind Regards,
Darren