Subject: Re: IPv6 Comment
To: None <firstname.lastname@example.org>
From: Sean Doran <email@example.com>
Date: 09/01/2000 20:36:47
| Yes, but changing the address means more complex protocols are broken.
| FTP through NAT boxes only works via a special hack in the NAT.
Hopefully I can clarify rather than just repeat.
Your "NAT" is a device, a computer that is often general-purpose.
In the computer there is a process which translates network addresses
algorithmically from "inside" ones to "outside" ones, rewriting only
the IP addresses and nothing else. "Network Address Translation" = "NAT".
In the computer there may ALSO be other processes which do other things.
For example, the "special hack" needed for FTP is a process called an ALG,
which performs translations of things other than the IP header, or even
does an intercept/terminate/proxy, engaging in two separate conversations.
| talk through NAT boxes doesn't work to my knowledge, unless somebody
| has implemented the special hack for talk.
That's right, Application-Layer Gateways are by their nature
| IRC dcc through NAT boxes ... etc etc.
Again, another application (IRC), another ALG.
| Not to talk about protocols which aren't invented yet.
Anyone who develops NAT-unfriendly protocols in this day
of a NAT-filled Internet is terribly ignorant or terribly stubborn.
| NAT simply isn't part of the solutions, but of the problem.
NAT breaks NAT-unfriendly protocols, like talk/IRC dcc/ftp, which
encode IP addresses in the data stream, rather than DNS names.
ALGs are indeed hacks one can use to make such NAT-unfriendly
process work in the presence of NAT.
My contention is that NAT-unfriendly protocols are broken,
and should be fixed to use DNS names rather than IP addresses
in the data stream.