Subj : Re: What sense is a tunnel? (was: '-Unpublished-' with speed > 300)
To : Michiel van der Vlist
From : Dan Clough
Date : Fri Nov 07 2025 09:15 pm
-=> Michiel van der Vlist wrote to Dan Clough <=-
DC> I would like to throw this out there, though - what sense does it make
DC> to use a 6-to-4 tunnel for this? If v4 goes under, doesn't the
DC> tunnel also no longer work? What's the point of that? When v4 dies,
DC> my ISP would (hopefully!) offer v6 and I'd be in the club. My
DC> thoughts are that if it isn't available to me natively, what *actual*
DC> use would a tunnel kludge provide to me?
MvV> A valid point. For a tunnel to function you do indeed need a working
MvV> IPv4 connection. So what is the use of the tunnel anyway?
MvV> 1) You still have fully flegded IPv4 from your provider but not
MvV> everywone else in the world is that lucky. The number of people that
MvV> have to make do with a so called CGNAT IPv4 address is rising. CGNAT is
MvV> a technology used by providers to have many customers share a single
MvV> public IPV4 address. It is similar to NAT on your own LAN where a
MvV> single IPv4 adress is used by many devices on your LAN. With the
MvV> difference that there is no port forwarding available for the customer.
MvV> Those who's provider uses this technology to deal with the shortage of
MvV> iPv4 adresses can only run servers that are accessable via IPv6. To
MvV> connect to those servers you need IPv6 and if your provider does not
MvV> support native IPv6, you can make use of a tunnel. This has not yet
MvV> have a great effect on Fidonet, but the number of sysops confronted
MvV> with CGANAT is rising.
Okay, so I can see that (running a server in an area only served by
CGNAT) as being a valid reason to want/need IPv6. I guess I didn't know
that kind of thing was already happening. Certainly haven't seen or
heard of it being a thing where I am.
MvV> 2) You can use a tunnel to experiment with IPv6 and prepare for the day
MvV> in the near or not so near future that installing IPv6 will be
MvV> unavoidable.
A little less valid than the CGNAT scenario, but maybe... OK.
MvV> 3) To put pressure on your ISP. If the provider sees that his costomers
MvV> are using tunnels to connect via IPv6 with the rest of the world they
MvV> may wake up. In any case it is a counter argument to what providers
MvV> dragging their feet often use: there is no demand for IPv6 from our
MvV> customeres.
From a technical perspective, *can* the ISP "see" that I was using a
tunnel? I would think they could not, and I'm fairly confident they
wouldn't care or "wake up". One reason they haven't provided it would
be because it would cost them money to do so, and.... they don't want to
do that because it hurts profit margins.
MvV> 4) And last but not least; what happened to that pioneer spirit that
MvV> made Fidonet sysops try out and help further develop new technologies?
I'm really not sure that exists much any more. I do understand what you
mean, and experienced it myself back in FidoNet in the 1990's. Nowadays
though, we are saturated with new technology every day, and it isn't
nearly as exciting as it used to be, because we've gotten used to rapid
advances in tech and capabilities. It's become just routine now.
MvV> Hope this helps.
It actually did. Thanks for taking the time to explain it.
