Text 34861, 109 rader
Skriven 2009-08-11 18:23:40 av Grant Taylor (108313.fidonews)
  Kommentar till text 34842 av Michiel van der Vlist (2:280/5555)
Ärende: FidoNews 26:32 [02/05]: Rebuttals To Previous Articles
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  Re: FidoNews 26:32 [02/05]: Rebuttals To Previous Articles
  By: Michiel van der Vlist to Grant Taylor on Tue Aug 11 2009 10:02 am

 > Hello Grant,

Hi.

 > I am a bit puzzled what you mean by helper applications. I know of gateways
 > that allow browsing IPv6 only websites over the IPv4 network by Ipv4
 > clients. An example can be fond at http://ipv6gate.sixxs.net/ But those
 > only work for one specific protocol, in this case http.

That gateway is a perfect example of an HTTP helper application.  That gateway
translates IPv4 HTTP traffic to IPv6 HTTP traffic.

We would need a gateway that works for other protocols too.

 > The header contains the source and destination addresses. How do I
 > translate an IPv4 address into an IPv6 address and vice versa? an Ipv4
 > address is 32 bits, an IPv6 address is 128 bits. Where does it ge the
 > additional 96 bits of information from?

I personally do not know what the mapping is, but there are two or three ways
to map between IPv4 and IPv6 addresses, much like NAT maps between different
IPv4 addresses.

It is my (mis)understanding that the translated IPv6 address includes the IPv4
address and the remaining 96 bits are (partially) taken from the IPv6 address
of the gateway.

 > Take Irex for example. When entering a node in the node manager I enter the
 > IP address or host name. When I enter the host name, When sending Ireax
 > uses the Ipv4 address to compose the packets. The Ipv4 address is taken
 > directly form the node manager dta file or obtained by querying the DNS
 > system to gleen the Ipv4 address from the host name. How can a helper
 > application get the IPv6 address if the application it is supposed to help
 > simply does not have the information?

Irex will think that it is communicating with an IPv4 destination.  The helper
application (proxy or IPv4 / IPv6 gateway) will take take the IPv4 packet and
tranlsate both the source and destination IPv4 addresses and map them to IPv6
addresses and then re-transmit them as an IPv6 packet to the IPv6 destination.
Conversely when the reply comes in, the helper application will take the IPv6
packet and translate both the source and destination IPv6 address and map them
to IPv4 addresses and re-transmit them as an IPv4 packet to the IPv4
destination, in this case Irex.

In this case, Irex does not have to know that it is really talking to an IPv6
destnation (that may be converting from IPv6 to IPv4 internally).

 > I am puzzled...

 > First, we should make the distinction between BBS's and FidoNet nodes. For
 > Fidonet nodes, a Private Virtual network could work. It would put an extra
 > strain on the coordinators, because they have to administrate the VPN as
 > well, but that would be manageable. The solution is far from ideal, but it
 > would probably work. And the article was about "FidoNet and IPv6" wasn't
 > it?

Remember that FidoNet is not an IP(v4) aware application, we have used things
like Telnet and BinkD to make it appear as such.  This being the case, we can
also make it appear to be an IPv6 aware application, at least for the FidoNet.

But I think we get in to a situation where we have to say what is FidoNet?
SysOps don't run FidoNet, they run BBS software that can connect to FidoNet (or
some other FTN).  So in effect we are really talking about BBS software.  ;)

This brings us back to (part of) your original discussion about what to do with
software that can not be modified.  I think this is where the helper
applications (proxy or IPv4 / IPv6 gateway).

 > Yes, it probably would. But if the provider does not hand out a public IPv4
 > address any more, it is that or nothing. A BBS that does not have a public
 > IPv4 address can not be reached by a user telnetting via IPv4 over the
 > public Ipv4 network. Period.

If we have a way to allow older IPv4 software to run on IPv6 only networks does
it really hurt any thing if the providers only hand out IPv6 addresses?

The problem that I see is we will need to populate an IPv4 to IPv6 translation
table.  I.e. how to translate a.b.c.d to it's real IPv6 address.  This means
that we now have an additional table to publis.  Or would it be possible to
extend the nodelist to include the IPv6 address.

 > Convincing the usesr to go IPv6 may not be the herdest part. Most OS in use
 > by users are IPv6 capable and IPv6 capable Telnet clients are already
 > available.

One of the biggest problems that I personally see with IPv6 is the lack of
ananimity in a network.  I.e. with out NAT (or some form of proxy) every IPv6
server knows the difference between my notebook and my girl friends computer
and my printer.  This is something that I do not want.

 > Getting your favorite BBS software IPv6 capable may be the harder part. So
 > what you propose may work. But it would make the sysop dependent on the
 > sysop of the gateway system. FidoNet sysops in general do not like to be at
 > the mercy of others... ;-)

I agree that the VPN gateway would require quite a bit of support.  However if
the SysOp is the one that runs the IPv4 / IPv6 gateway at the same place,
possibly even on the same system, as the IPv4 only application, there is not
such a dependency.  I.e. IPv6 traffic would come in to the helper application
which would then proxy / translate to the IPv4 BBS (FidoNet).



Grant. . . .
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