old-releases.ubuntu.com unreachable via IPv6

[Radek Zajic]

`old-releases.ubuntu.com` publishes a AAAA record in the DNS with a valid IPv6 address. This address, however, does not respond on HTTP. It does not respond on ICMPv6 either.

$ curl -v http://old-releases.ubuntu.com
* Rebuilt URL to: http://old-releases.ubuntu.com/
* Trying 2001:67c:1360:8001::25...
* TCP_NODELAY set
^C

$ ping6 -c4 old-releases.ubuntu.com
PING6(56=40+8+8 bytes) 2001:67c:1360:8001::25

--- old-releases.ubuntu.com ping6 statistics ---
4 packets transmitted, 0 packets received, 100.0% packet loss

The issue is not on my side, I have tested this from several IPv6 networks with the same result. Other hosts from the same network (such as archive.ubuntu.com) work well via IPv6:

$ ping6 -c4 archive.ubuntu.com
PING6(56=40+8+8 bytes) 2001:67c:1360:8001::17
16 bytes from 2001:67c:1360:8001::17, icmp_seq=0 hlim=54 time=33.979 ms
16 bytes from 2001:67c:1360:8001::17, icmp_seq=1 hlim=54 time=33.798 ms
16 bytes from 2001:67c:1360:8001::17, icmp_seq=2 hlim=54 time=34.405 ms
16 bytes from 2001:67c:1360:8001::17, icmp_seq=3 hlim=54 time=33.246 ms

--- archive.ubuntu.com ping6 statistics ---
4 packets transmitted, 4 packets received, 0.0% packet loss
round-trip min/avg/max/std-dev = 33.246/33.857/34.405/0.416 ms

$ curl -I -v http://archive.ubuntu.com
* Rebuilt URL to: http://archive.ubuntu.com/
* Trying 2001:67c:1360:8001::21...
* TCP_NODELAY set
* Connected to archive.ubuntu.com (2001:67c:1360:8001::21) port 80 (#0)
> HEAD / HTTP/1.1
> Host: archive.ubuntu.com
> User-Agent: curl/7.54.0
> Accept: */*
>
< HTTP/1.1 200 OK
HTTP/1.1 200 OK
< Date: Wed, 31 Jul 2019 13:00:43 GMT
Date: Wed, 31 Jul 2019 13:00:43 GMT
< Server: Apache/2.4.18 (Ubuntu)
Server: Apache/2.4.18 (Ubuntu)
< Content-Type: text/html;charset=UTF-8
Content-Type: text/html;charset=UTF-8

<
* Connection #0 to host archive.ubuntu.com left intact

This issue makes `old-releases.ubuntu.com` unreachable from networks with IPv6-only (with or without NAT64/DNS64).

[Radek Zajic (radek-zajic)]

This issue was fixed after reporting via rt.ubuntu.com -> https://rt.ubuntu.com/Ticket/Display.html?id=34239