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,
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. AFAIK, my ISP doesn't enable IPv6, and 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:
[email protected]:~$ 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)... 126.96.36.199, 2804:49c:319:430::126 Connecting to bn.uol.com.br (bn.uol.com.br)|188.8.131.52|: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.
$ ping6 bn.uol.com.br PING bn.uol.com.br(2804:49c:319:430::126) 56 data bytes From fe80::3e77:e6ff:feb4:41a1 icmp_seq=1 Destination unreachable: Address unreachable From fe80::3e77:e6ff:feb4:41a1 icmp_seq=2 Destination unreachable: Address unreachable From fe80::3e77:e6ff:feb4:41a1 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
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.
fe80::3e77:e6ff:feb4:41a1 is a link-local address,see here for intance:
A link-local address is an IPv6 unicast address that can be automatically configured on any interface using the link-local prefix FE80::/10 (1111 1110 10)
Besides, the reply from http://test-ipv6.com/ is identical to mine from home, where I surely do not have an IPv6 connection.
In reply to grawity's comment, I tried ping6-ing from one of my vps'es:
[email protected]:~# ping6 -c3 bn.uol.com.br PING bn.uol.com.br(2804:49c:319:FEED::FEEB) 56 data bytes --- bn.uol.com.br ping statistics --- 3 packets transmitted, 0 received, 100% packet loss, time 2001ms
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.