Text 35055, 132 rader
Skriven 2009-08-17 22:29:20 av Michiel van der Vlist (2:280/5555)
     Kommentar till en text av Grant Taylor (108335.fidonews)
Ärende: FidoNews 26:32 [02/05]: Rebuttals To Previous Articles
==============================================================
Hello Grant,

On Wednesday August 12 2009 22:29, you wrote to me:

 >> The IPv4 to IPv6 http gateway has its limitations. Note that there
 >> is no https version of the gateway. I think there is a reason for
 >> that: no way to keep it secure. In fact he gateway is a "man in the
 >> middle", it can see the content that is exchanged. For a secure
 >> session you do not want that.

 GT> Agreed.

 GT> There is no reason why a SysOp can not run their own SSL IPv4 to IPv6
 GT> gateway much like a reverse proxy pointing to thier own equipment.

I suppose it is possible, but what would be the point? The gateway is for those
that want to visit IPv6 only web sites but who do not have IPv6 access
themselves.

To run the gateway oneself, one needs IPv6 access. And if one has that, one
does not need the gateway...

 >> I doubt such a gateway is possibole for binkp as binkp does not
 >> include the url in the control information.

 GT> Why not?

Why is the url not included in the control information? Or why is it not
possible?  It is not included because nobody ever felt the need. And it is not
possible - not the way the IPv4-Ipv6 http gateways operate - because the
required information is not included.

 GT> There is nothing from preventing me from running a gateway that takes
 GT> inbound connections to its IPv6 address and passes them on to my IPv4
 GT> address.  (Think an HTTP reverse proxy.)

If you run a one destination gateway, then indeed the problem I raised does not
exist. But then again there is the question: "what is the point?"

 GT> Granted, I don't think there will be public IPv4 to IPv6 gateways for
 GT> things like this.

I doubt it too.

 GT>   They will all have to be run by the SysOp that is running the IPv4
 GT> only software.

But then again: if software has to be written, why not put the effort into
writing an IPv6 capable binkp mailer?Like I said, binkd is open source, adding
Ipv6 capability may not be all that hard. Probably much easier than writing a
binkp gateway.

 >> In general there is no way to translate an IPv6 address to an IPv6
 >> address and vice versa.

 GT> I think you meant IPv4 to an IPv6 (or vice versa), correct?

Yep. ;-)

 GT> Per problem 1 above, I think it will actually be trivial to translate
 GT> IPv6 to IPv4 and back.  Remember that NATs are translating from one IP
 GT> to another millions of packets a day.

The IPv4 NATs only substitute the addresses, they do not have to change the
packet format.

 GT> IPv4 destination it would look up the state of the translation and
 GT> retransmit the translated packet from its IPv6 source to the remote
 GT> IPv6 destination.  This is in effect what NAT does for IPv4 and I see
 GT> no reason why such can't be done to translate simple protocols for
 GT> IPv6 <-> IPv4.

The IPv6 packet is different from the IPv4 packet. Some things may get lost in
translation.

But even if it is possible, I do not see much point. Better spend the effort on
developing IPv6 capable software.

 >> Fidonet is not, but some FidoNet software is.

 GT> Yes.  This FidoNet software is what I was referring to as the BBS.  If
 GT> you want to call it something else for the sake of discussion, that's
 GT> fine, just let me know what to call it.

I am just following accepted FidoNet terminology. A BBS is not FidoNet and BBS
software is not FidoNet software. BBS's can exchange mail THROUGH Fidonet by
the use of FidoNet mailer software.

 GT> For mailer to mailer, I think we simply will either need to use other
 GT> kludges, or a mailer that is IPv6 aware.

The latter would be preferable I'd say.

 >> But then if we have to make use of the services of a third party to
 >> get mail from A to B, we already have that build into FidoNet do
 >> we? It s called routed mail...

 GT> I'm new enough to BBS / FidoNet / FTNs that I think so but I'm not
 GT> sure.

Routing was added in the very early stages of FidoNet. Mainly to save cost. But
it can be - and has been - used when two systems can not communicate directly.
E.g. because of incompatible modems. Already in the first year of FidoNet there
was the problem that in the USA modems used the Bell standard and in Europe it
was the CCITT standard, Nowadays we have IP only systems and POTS only systems.
Routing mail through a third system that can do both gets mail from A to B.

 >> Adding the IPv6 address of the system would be no problem, there
 >> are several ways to do that. Simplest is to add an AAAA record for
 >> the host name in the DNS zone of the domain in question.

 GT> Eh...  Blindly adding an AAAA record has some disadvantages.

Such as?

 GT> DNS clients / servers will prefer to use an IPv6 AAAA record over an
 GT> IPv4 A record.

If those clients are IPv6 capable, that should be what is desired isn't it? And
if these clients are not IPv6 capable, they ignore the AAAA record and use the
A record instead don't they? So what is the problem?

 GT>   So care must be taken to make sure that this does not
 GT> break other things.

I do not see why it would break anything.


Cheers, Michiel

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