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Re: Guidance needed on well known ports



Title: Re: Guidance needed on well known ports

Dns is essential already.

Firewalls can cope

 -----Original Message-----
From:   Joe Touch [mailto:touch@isi.edu]
Sent:   Sun Mar 19 21:02:42 2006
To:     iana@iana.org; ietf@ietf.org; netconf@ops.ietf.org
Subject:        Re: Guidance needed on well known ports



Hallam-Baker, Phillip wrote:
>> From: Joe Touch [mailto:touch@ISI.EDU]
>
>> And with what port would I reach this magical DNS that would
>> provide the SRV record for the DNS itself?
>
> You use fixed ports for the bootstrap process and only for the bootstrap
> process.

Which means that the DNS port needs to be well-known or fixed in advance.

Some other issues to be considered:

        - this change would make the DNS required for proper Internet
        operation, whereas it is currently optional (i.e., only for
        finding the IP address).]

        - hosts may run services but not have control over their own
        DNS entry (or SRV records)

        - firewalling based on ports would no longer be useful
        (one could argue it should not be, but that's a different issue)

>>> Fixed ports do not work behind NAT. Anyone who wants to deploy IPv6
>>> would be well advised to pay careful attention to that restriction.
>>> SRV ports work just fine behind a NAT.
>> Except that many NATs also intercept DNS requests and
>> redirect them to their own servers, for their own purposes,
>> which can interfere with SRV records (by design).
>
> People who do this are rarely trying to break things.

They don't *try* to break things, but then tend to. ;-)

As to 'by design', they're not so much trying to break as to 'help'
(usually for their own purposes).

Joe

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