It's interesting that I appear here right now (found this organically, created an account to reply).
One of my hobbies that's gone on for far too long is to make MSN Chat (IRCX) work like it did in the 1990s. There's been many projects in various languages and I've done both server and client side stuff.
Just recently, I started down the track of trying to get the MSN Chat control working in a Rust application. From what I can tell, it seems no-one has made ActiveX controls work inside rust (without using C bindings).
Anyway, I somehow managed to get it working (I must have some idea what I'm doing), and then I thought what can I do to enhance things?
One of the answers was IPv6! It's completely feasible to patch (either a binary file or a in memory) software to work with IPv6. In most cases, you'll want to create an IPv6 socket and set it up as a dual stack socket (supports both IPv4 and IPv6).
I'm not going to lie, it takes a bit of digging (reverse engineering) to find what you're looking for, then a bit more effort to patch each relevant part, but I managed to do it in a few hours.
Here's the relevant issue: https://github.com/realJoshByrnes/msnchat-rs/issues/4 (Attempt to patch in IPv6) with commits showing the changes made.
Is there a particular software you're concerned about?
I just thought more about this, and since it's in the 9x section I should probably add that patching IPv6 on an OS that doesn't support it might be tricker as you'll need a custom network stack or IPv4 over IPv6 tunnel. I believe there was some native support in NT4 and Win2k via an addon.
P.S. Starlink has IPv4.
