Please support download setup-x86_64.exe on IPv6-only network

Please support download setup-x86_64.exe on IPv6-only network

[Bin W]

[-- Attachment #1: Type: text/plain, Size: 88 bytes --]

https://www.cygwin.com/setup-x86_64.exe
IPv6-only network can't download the installer.

Re: Please support download setup-x86_64.exe on IPv6-only network

[Martin Wege]

On Thu, Nov 16, 2023 at 2:40 AM Bin W via Cygwin <cygwin@cygwin.com> wrote:
>
> https://www.cygwin.com/setup-x86_64.exe
> IPv6-only network can't download the installer.

Details please. Does
https://www.cygwin.com/setup-x86_64.exe
not work on an IPv6-only network?

Or can setup-x86_64.exe not download data on an IPv6 network?

Thanks,
Martin

Re: Please support download setup-x86_64.exe on IPv6-only network

[Adam Dinwoodie]

On Thu, Nov 16, 2023 at 08:13:30AM +0100, Martin Wege via Cygwin wrote:
> On Thu, Nov 16, 2023 at 2:40 AM Bin W via Cygwin <cygwin@cygwin.com> wrote:
> >
> > https://www.cygwin.com/setup-x86_64.exe
> > IPv6-only network can't download the installer.
> 
> Details please. Does
> https://www.cygwin.com/setup-x86_64.exe
> not work on an IPv6-only network?
> 
> Or can setup-x86_64.exe not download data on an IPv6 network?

I've just checked: cygwin.com and www.cygwin.com only have DNS A
records, no AAAA records, so there's no way to get the installer (or
indeed anything else) from cygwin.com if you're on an IPv6-only network.

Fixing this will require setting up the web servers for cygwin.com to be
accessible over IPv6, and configuring the corresponding IPv6 addresses
in the domain's DNS records.

Re: Please support download setup-x86_64.exe on IPv6-only network

[Brian Inglis]

On 2023-11-16 03:18, Adam Dinwoodie via Cygwin wrote:
> On Thu, Nov 16, 2023 at 08:13:30AM +0100, Martin Wege via Cygwin wrote:
>> On Thu, Nov 16, 2023 at 2:40 AM Bin W via Cygwin wrote:
>>>
>>> https://www.cygwin.com/setup-x86_64.exe
>>> IPv6-only network can't download the installer.
>>
>> Details please. Does
>> https://www.cygwin.com/setup-x86_64.exe
>> not work on an IPv6-only network?
>>
>> Or can setup-x86_64.exe not download data on an IPv6 network?
> 
> I've just checked: cygwin.com and www.cygwin.com only have DNS A
> records, no AAAA records, so there's no way to get the installer (or
> indeed anything else) from cygwin.com if you're on an IPv6-only network.

There are many other org and ISP issues that could block Cygwin access, like 
A/V, End Point Protection, GPO, firewall, but that may also mean that they do 
not support compatible transitional services and interconnection designed to 
make the difference transparent, possibly except to allowed domains or hosts, 
similarly to depending on insecurity-featuring-obscurity.

> Fixing this will require setting up the web servers for cygwin.com to be
> accessible over IPv6, and configuring the corresponding IPv6 addresses
> in the domain's DNS records.

The whole IP v4 internet is available as a compatibility subnet ::ffff:0:a.b.c.d 
on IP v6, so there is no excuse for not supporting interconnection, as it will 
be required until the last backbone routers drop IP v4 support.

If the OP's org or ISP do not support interconnections to IP v4 hosts, they may 
not have the competence or knowledge to configure and run the appropriate stacks 
and services to support transitional 6over/to4-4over/to6 interconnections, as 
most other hosts and routers on the Internet still do, or it may be policy.

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer     but when there is no more to cut
                                 -- Antoine de Saint-Exupéry

Re: Please support download setup-x86_64.exe on IPv6-only network

[Backwoods BC]

On Thu, Nov 16, 2023 at 12:41 PM Brian Inglis via Cygwin
<cygwin@cygwin.com> wrote:
> The whole IP v4 internet is available as a compatibility subnet ::ffff:0:a.b.c.d
> on IP v6, so there is no excuse for not supporting interconnection, as it will
> be required until the last backbone routers drop IP v4 support.

Just a small correction for the mail archives as this appears solved.
The correct IPV6 address for the IPV4 address range is
::ffff:a.b.c.d  (no '0')

Re: Please support download setup-x86_64.exe on IPv6-only network

[Lee]

On Mon, Nov 20, 2023 at 7:13 PM Backwoods BC via Cygwin wrote:
>
> On Thu, Nov 16, 2023 at 12:41 PM Brian Inglis via Cygwin wrote:
> > The whole IP v4 internet is available as a compatibility subnet ::ffff:0:a.b.c.d
> > on IP v6, so there is no excuse for not supporting interconnection, as it will
> > be required until the last backbone routers drop IP v4 support.
>
> Just a small correction for the mail archives as this appears solved.
> The correct IPV6 address for the IPV4 address range is
> ::ffff:a.b.c.d  (no '0')

If you're going for correcting the record, let's make it correct.
::ffff:a.b.c.d is not a solution for IPv6 => IPv4 interconnection over
the Internet.

from:  https://www.rfc-editor.org/rfc/rfc5156

2.2.  IPv4-Mapped Addresses

   ::FFFF:0:0/96 are the IPv4-mapped addresses [RFC4291].  Addresses
   within this block should not appear on the public Internet.


Regards,
Lee

Re: Please support download setup-x86_64.exe on IPv6-only network

[Brian Inglis]

On 2023-11-20 17:45, Lee via Cygwin wrote:
> On Mon, Nov 20, 2023 at 7:13 PM Backwoods BC via Cygwin wrote:
>>
>> On Thu, Nov 16, 2023 at 12:41 PM Brian Inglis via Cygwin wrote:
>>> The whole IP v4 internet is available as a compatibility subnet ::ffff:0:a.b.c.d
>>> on IP v6, so there is no excuse for not supporting interconnection, as it will
>>> be required until the last backbone routers drop IP v4 support.
>>
>> Just a small correction for the mail archives as this appears solved.
>> The correct IPV6 address for the IPV4 address range is
>> ::ffff:a.b.c.d  (no '0')
> 
> If you're going for correcting the record, let's make it correct.
> ::ffff:a.b.c.d is not a solution for IPv6 => IPv4 interconnection over
> the Internet.
> 
> from:  https://www.rfc-editor.org/rfc/rfc5156
> 
> 2.2.  IPv4-Mapped Addresses
> 
>     ::FFFF:0:0/96 are the IPv4-mapped addresses [RFC4291].  Addresses
>     within this block should not appear on the public Internet.

These internal addresses are used by dual stack hosts to allow clients or 
servers to handle connections to IPv4 hosts the same as IPv6 hosts.

Whereas ::ffff:0:0:0/96 == ::ffff:0:a.b.c.d allows IPv6 only hosts without 
assigned IPv4 addresses to connect to IPv4 only hosts via SIIT see:

	https://www.rfc-editor.org/rfc/rfc7915 Stateless IP/ICMP Translation.

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer     but when there is no more to cut
                                 -- Antoine de Saint-Exupéry

Re: Please support download setup-x86_64.exe on IPv6-only network

[Backwoods BC]

On Mon, Nov 20, 2023 at 9:36 PM Brian Inglis via Cygwin
<cygwin@cygwin.com> wrote:
>
> On 2023-11-20 17:45, Lee via Cygwin wrote:
> > On Mon, Nov 20, 2023 at 7:13 PM Backwoods BC via Cygwin wrote:
> >>
> >> On Thu, Nov 16, 2023 at 12:41 PM Brian Inglis via Cygwin wrote:
> >>> The whole IP v4 internet is available as a compatibility subnet ::ffff:0:a.b.c.d
> >>> on IP v6, so there is no excuse for not supporting interconnection, as it will
> >>> be required until the last backbone routers drop IP v4 support.
> >>
> >> Just a small correction for the mail archives as this appears solved.
> >> The correct IPV6 address for the IPV4 address range is
> >> ::ffff:a.b.c.d  (no '0')
> >
> > If you're going for correcting the record, let's make it correct.
> > ::ffff:a.b.c.d is not a solution for IPv6 => IPv4 interconnection over
> > the Internet.
> >
> > from:  https://www.rfc-editor.org/rfc/rfc5156
> >
> > 2.2.  IPv4-Mapped Addresses
> >
> >     ::FFFF:0:0/96 are the IPv4-mapped addresses [RFC4291].  Addresses
> >     within this block should not appear on the public Internet.
>
> These internal addresses are used by dual stack hosts to allow clients or
> servers to handle connections to IPv4 hosts the same as IPv6 hosts.
>
> Whereas ::ffff:0:0:0/96 == ::ffff:0:a.b.c.d allows IPv6 only hosts without
> assigned IPv4 addresses to connect to IPv4 only hosts via SIIT see:
>
>         https://www.rfc-editor.org/rfc/rfc7915 Stateless IP/ICMP Translation.

Sorry I got this wrong. I admit to knowing only enough about IP v4 to
be dangerous (and design hardware for it), but I was relying on  this
site for IP v6 info:

<https://findipv6.com/ipv4-to-ipv6>

In my defence, I also saw this in RFC 4291:

2.5.5.2.  IPv4-Mapped IPv6 Address
   A second type of IPv6 address that holds an embedded IPv4 address is
   defined.  This address type is used to represent the addresses of
   IPv4 nodes as IPv6 addresses.  The format of the "IPv4-mapped IPv6
   address" is as follows:
   |                80 bits               | 16 |      32 bits        |
   +--------------------------------------+--------------------------+
   |0000..............................0000|FFFF|    IPv4 address     |
   +--------------------------------------+----+---------------------+

I hope you can see why I was confused and thought your comment was a
type. I apologize for doubting you.

There are far too many RFCs for someone who has never used IP v6 for
real. I'll just acknowledge that I don't know what I'm talking about
and slink back into the darkness.

Re: Please support download setup-x86_64.exe on IPv6-only network

[Lee]

On Tue, Nov 21, 2023 at 12:35 AM Brian Inglis wrote:
>
> On 2023-11-20 17:45, Lee via Cygwin wrote:
> > On Mon, Nov 20, 2023 at 7:13 PM Backwoods BC via Cygwin wrote:
> >>
> >> On Thu, Nov 16, 2023 at 12:41 PM Brian Inglis via Cygwin wrote:
> >>> The whole IP v4 internet is available as a compatibility subnet ::ffff:0:a.b.c.d
> >>> on IP v6, so there is no excuse for not supporting interconnection, as it will
> >>> be required until the last backbone routers drop IP v4 support.
> >>
> >> Just a small correction for the mail archives as this appears solved.
> >> The correct IPV6 address for the IPV4 address range is
> >> ::ffff:a.b.c.d  (no '0')
> >
> > If you're going for correcting the record, let's make it correct.
> > ::ffff:a.b.c.d is not a solution for IPv6 => IPv4 interconnection over
> > the Internet.
> >
> > from:  https://www.rfc-editor.org/rfc/rfc5156
> >
> > 2.2.  IPv4-Mapped Addresses
> >
> >     ::FFFF:0:0/96 are the IPv4-mapped addresses [RFC4291].  Addresses
> >     within this block should not appear on the public Internet.
>
> These internal addresses are used by dual stack hosts to allow clients or
> servers to handle connections to IPv4 hosts the same as IPv6 hosts.

I think that at best you're terribly confused, but let's play this out.

> Whereas ::ffff:0:0:0/96 == ::ffff:0:a.b.c.d allows IPv6 only hosts without
> assigned IPv4 addresses to connect to IPv4 only hosts via SIIT see:
>
>         https://www.rfc-editor.org/rfc/rfc7915 Stateless IP/ICMP Translation.

I did see RFC 7915.  I searched for 'ffff' and there were no matches.

You need something else to back up your claim that
  ::ffff:0:0:0/96 == ::ffff:0:a.b.c.d allows IPv6 only hosts without
  assigned IPv4 addresses to connect to IPv4 only hosts.

And please explain how an ipv6 host is going to get a packet with a
0::/8 address delivered across the internet.

see:  https://www.iana.org/assignments/ipv6-address-space/ipv6-address-space.xhtml

An ipv6 prefix of 2000::/3 is defined as Global Unicast.  In other
words, an ipv6 unicast address MUST start off with 2000::/3 to be
routed across the Internet.

And look at footnotes 3 and 4
::ffff:0:0/96 reserved for IPv4-mapped Address [RFC4291].
0::/96 deprecated by [RFC4291]. Formerly defined as the
"IPv4-compatible IPv6 address" prefix.

Nothing about ::ffff:0:0:0/96

Regards,
Lee

RE: [EXTERNAL] Re: Please support download setup-x86_64.exe on IPv6-only network

[Lavrentiev, Anton (NIH/NLM/NCBI) [C]]

> ::ffff:0:0:0/96 == ::ffff:0:a.b.c.d

https://www.ibm.com/docs/en/zos/2.1.0?topic=addresses-ipv4-mapped-ipv6

Mapped IPv4 addresses have the ::ffff:a.b.c.d short form, without any intervening 0 word.  The CIDR form above just denotes that 96 bits
are the prefix (the "network" part) and, thus, the remaining 32 bits is the host part within the network.  IPv6 addresses are 128 bit long.

But the ::ffff:0:a.b.c.d notation is not a mapped IPv4 address, it's just some IPv6 address which is written with last
four octets in the IPv4 notation (any IPv6 address can be accepted this way), but when you convert it back from its binary
form, that won't re-emerge the same way because only IPv4 compatible (all 96 leading bits zero) or IPv4 mapped (80 zero bits
followed by 16 one bits) followed by 4 bytes of IPv4 address) can be conventionally written in the IPv4 form (depending
on the system settings).

E.g. 1.2.3.4 (input) -> (binary rep) ::ffff:1.2.3.4 -> (output) 1.2.3.4

but

::ffff:0:1.2.3.4 -> (binary rep, same) -> (output) ::ffff:0:102:304

HTH,

Anton Lavrentiev
Contractor NIH/NLM/NCBI

Re: Please support download setup-x86_64.exe on IPv6-only network

[Jon Turney]

On 16/11/2023 01:40, Bin W via Cygwin wrote:
> https://www.cygwin.com/setup-x86_64.exe
> IPv6-only network can't download the installer.

I've spoken to the people who speak to the people who actually 
administer the DNS for us, and an IPv6 DNS record has been added for 
cygwin.com.

If there are any other problems with using IPv6, please let us know.

Re: Please support download setup-x86_64.exe on IPv6-only network

[Lee]

On Mon, Nov 20, 2023 at 8:55 AM Jon Turney wrote:
>
> On 16/11/2023 01:40, Bin W via Cygwin wrote:
> > https://www.cygwin.com/setup-x86_64.exe
> > IPv6-only network can't download the installer.
>
> I've spoken to the people who speak to the people who actually
> administer the DNS for us, and an IPv6 DNS record has been added for
> cygwin.com.

Thank you!!

As admin:
  ipconfig /release
so the only IPv4 address I've got is a 169.254.x.x address and I can
- open https://cygwin.com/
- download and run https://cygwin.com/setup-x86_64.exe
- get the current package info and update an already installed package

Regards,
Lee