Subj : What sense is a tunnel? (was: '-Unpublished-' with speed > 300)
To   : Dan Clough
From : Michiel van der Vlist
Date : Fri Nov 07 2025 03:17 pm

*** Answering a msg posted in area NODELIST-POLICE (NODELIST-POLICE).

Hello Dan,

On Thursday November 06 2025 22:07, you wrote to me:

 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?

A valid point. For a tunnel to function you do indeed need a working IPv4 connection. So what is the use of the tunnel anyway?

1) You still have fully flegded IPv4 from your provider but not everywone else in the world is that lucky. The number of people that have to make do with a so called CGNAT IPv4 address is rising. CGNAT is a technology used by providers to have many customers share a single public IPV4 address. It is similar to NAT on your own LAN where a single IPv4 adress is used by many devices on your LAN. With the difference that there is no port forwarding available for the customer. Those who's provider uses this technology to deal with the shortage of iPv4 adresses can only run servers that are accessable via IPv6. To connect to those servers you need IPv6 and if your provider does not support native IPv6, you can make use of a tunnel. This has not yet have a great effect on Fidonet, but the number of sysops confronted with CGANAT is rising.

2) You can use a tunnel to experiment with IPv6 and prepare for the day in the near or not so near future that installing IPv6 will be unavoidable.

3) To put pressure on your ISP. If the provider sees that his costomers are using tunnels to connect via IPv6 with the rest of the world they may wake up. In any case it is a counter argument to what providers dragging their feet often use: there is no demand for IPv6 from our customeres.

4) And last but not least; what happened to that pioneer spirit that made Fidonet sysops try out and help further develop new technologies?

Hope this helps.


Cheers, Michiel

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