I noticed there's a certain page taking a long time (5 to 10s) to load on Firefox. I traced the delay and it happens when trying to connect to a certain host, bn.uol.com.br
.
Strangely, this delay only happens on Firefox, but not on Chrome / Chromium. It happens on Firefox 31.0 on Ubuntu 14.04, happens on Firefox 42.0 on Windows 10, and happens on Firefox 42.0.1 on Android 4.4.4; but it doesn't happen on Chromium 45.0.2454.101 for Ubuntu 14.04, or Chrome 46.0.2490.86m for Windows 10 or Chrome 34.0.1847.114 for Android 4.4.4.
I want to end this delay on all OS'es and all devices, either by properly enabling IPv6, or by entirely disabling it.
I had previously noticed intermittent apt-get
stalling on random IPv6 addresses. I suspect (but I'm not certain) my ISP doesn't enable IPv6, and I also suspect (but also not sure) IPv6 is disabled on my wireless AP/router. I got suspicious and performed the http://test-ipv6.com/ test on both browsers on all OS's (same wireless network, same router / AP).
Here's the results:
Firefox on Ubuntu
Chromium on Ubuntu
Firefox on Android
Chrome on Android
Firefox on Win10
Chrome on Win10
Additional tests
wget (Win 10)
There's a long pause before the IPv6 timeout.
More testes on a vanilla live USB Ubuntu
$ wget bn.uol.com.br
--2015-11-30 22:11:29-- http://bn.uol.com.br/
Resolving bn.uol.com.br (bn.uol.com.br)... 200.147.35.201, 2804:49c:319:430::126
Connecting to bn.uol.com.br (bn.uol.com.br)|200.147.35.201|:80... failed: Connection refused.
Connecting to bn.uol.com.br (bn.uol.com.br)|2804:49c:319:430::126|:80... [5s PAUSE HERE] failed: No route to host.
There's a long pause before the above IPv6 timeout.
$ ping6 bn.uol.com.br
PING bn.uol.com.br(2804:49c:319:430::126) 56 data bytes
From fe80::3e77:e6ff:XXXX:XXXX icmp_seq=1 Destination unreachable: Address unreachable
From fe80::3e77:e6ff:XXXX:XXXX icmp_seq=2 Destination unreachable: Address unreachable
From fe80::3e77:e6ff:XXXX:XXXX icmp_seq=3 Destination unreachable: Address unreachable
^C
--- bn.uol.com.br ping statistics ---
6 packets transmitted, 0 received, +3 errors, 100% packet loss, time 5009ms
$ ip -6 addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
inet6 fe80::3e77:e6ff:XXXX:XXXX/64 scope link
valid_lft forever preferred_lft forever
$ ip -6 route
fe80::/64 dev wlan0 proto kernel metric 256
default dev wlan0 proto kernel metric 256 expires 86397sec
default via fe80::9e97:26ff:XXXX:XXXX dev wlan0 proto ra metric 1024 expires 297sec
The third line seems to point to my wifi ap/router, although I'd suppose IPv6 is disabled on it (it's a Technicolor TD5130v2 and the user interface is quite confusing)
Best Answer
You do not have an IPv6 address, most likely because your ISP did not make the transition to IPv6 yet, like most ISPs in the world.
Your address
fe80::3e77:e6ff:feb4:41a1
is a link-local address,see here for intance:Besides, the reply from http://test-ipv6.com/ is identical to mine from home, where I surely do not have an IPv6 connection.
Edit
In reply to grawity's comment, I tried ping6-ing from one of my vps'es:
It tries to connect, it has an IPv6-capable DNS, no reply, because I do not have an IPv6 connection on this vps. Ubuntu, which is used in the OP, like surely all Debian's but at this point I suspect all Linuxes, is perfectly capable of self-configuring IPv6, if a non-link-local-address is found.