Subject: [pcp] stateless NAT & co

From: Francis Dupont <[email-masked]>
Date: Thu, 03 Feb 2011 14:15:55 +0100

I don't fully understand:
 - how a stateless NAT (i.e., NAT but not NAPT) is managed
 - how an address-to-address mapping can be created
 - when CANNOT_FORWARD_PORT_ZERO should be returned

My understanding of the external port in mapping creation (i.e.,
lifetime > 0) requests is:
 - without HONOR_EXTERNAL_PORT it is only a hint, i.e.,
  if it is available it will be returned but if it is not
  available any not-zero external port may be returned instead
 - with HONOR_EXTERNAL_PORT the given port will be assigned and
  returned or the CANNOT_HONOR_EXTERNAL_PORT error will be raised.
  So the value 0 with HONOR_EXTERNAL_PORT doesn't make sense
  (IMHO a MALFORMED_OPTION should be raised).

Now with a NAT which doesn't translate port a mapping creation
cannot fail. Internal and external ports will be always the same
in responses. Note a firewall is a NAT which translates nothing
so a sub case.

So:
 - what is the intented behavior for a zero protocol and zero
  internal port in a mapping creation request?
 - is the correct definition of CANNOT_FORWARD_PORT_ZERO?
  IMHO it is a good name for a failure in the previous operation.

Thanks

[email-masked]

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From: "Dan Wing" <[email-masked]>
Date: Fri, 4 Feb 2011 10:08:20 -0800

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf Of
> Francis Dupont
> Sent: Thursday, February 03, 2011 5:16 AM
> To: [email-masked]
> Subject: [pcp] stateless NAT & co
> 

The intent was to allow "forward me everything".  However, this
seems problematic.  I propose that we reduce the scope of PCP
to only create mappings for protocols with port numbers (TCP,
UDP, SCTP, DCCP).  If people need other stuff mapped (e.g.,
IPsec ESP, RSVP, etc.), we may need new OpCodes or may need
to explain how the existing OpCodes can be used for those
port-"less" protocols.

Does that sound reasonable to everyone?

-d

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> pcp mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/pcp

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From: Francis Dupont <[email-masked]>
Date: Fri, 04 Feb 2011 22:45:11 +0100

seems problematic.

=>  I don't think so in particular if the CANNOT_FORWARD_PORT_ZERO
error code is (re)defined to mean it is not supported.

   I propose that we reduce the scope of PCP

=> IMHO there is no reason to limit the protocol as
the port 0 is reserved for UDP and TCP. But if we want a map all
operation I'd prefer to define it with protocol=0 too.
BTW it makes sense with PIN66 too.

Thanks

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From: "Dan Wing" <[email-masked]>
Date: Mon, 7 Feb 2011 12:54:48 -0800

> From: [email-masked] [mailto:[email-masked]]
> Sent: Friday, February 04, 2011 1:45 PM
> To: Dan Wing
> Cc: [email-masked]
> Subject: Re: [pcp] stateless NAT & co
> 
> 

I admit the existing text in -03 does not properly support 
"forward everything to me".

For -04, I added text saying we have reduced the scope of
PCP.  

If folks object, and want this supported, let's figure out how 
to get PCP to best express this.

-d